Fluid-assisted medical devices, systems and methods

ABSTRACT

An electrosurgical device is provided which comprises a distal portion having a bipolar electrode configuration and at least one fluid outlet opening. The device further includes a first electrode tip spaced from a second electrode tip with the first electrode tip to serve as a first pole of the bipolar electrode configuration and the second electrode tip to serve as a second pole of the bipolar electrode configuration. The first and second electrode tips are configured to slide over a tissue surface in the presence of a fluid provided from the fluid outlet opening and an electrical current provided from the electrode tips.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a National Stage application of PCT patentapplication Ser. No. PCT/US02/28488, filed Sep. 5, 2002, which claimspriority to U.S. provisional application Ser. No. 60/368,177, filed Mar.27, 2002, and Ser. No. 60/356,390, filed Feb. 12, 2002, and which is acontinuation-in-part of U.S. patent application Ser. No. 09/947,658,filed Sep. 5, 2001, now U.S. Pat. No. 7,115,139, which is acontinuation-in-part of U.S. patent application Ser. No. 09/797,049,filed Mar. 1, 2001, now U.S. Pat. No. 6,702,810, which claims priorityto U.S. provisional application Ser. No. 60/187,114, filed Mar. 6, 2000.

This patent application is also a continuation-in-part of U.S. patentapplication Ser. No. 10/354,643, filed Jan. 29, 2003, now U.S. Pat. No.7,651,494, which is a continuation of U.S. patent application Ser. No.09/668,403, filed Sep. 22, 2000, now U.S. Pat. No. 6,558,385.

The entire disclosure of each of these patent applications except forU.S. patent application Ser. No. 10/354,643 is incorporated herein byreference to the extent it is consistent, notwithstanding otherincorporation by reference statementys appearing elsewhere in thisapplication.

This application is being filed as a PCT International Patentapplication in the name of TissueLink Medical, Inc. (a U.S. nationalcorporation), for the designation of all countries except the US, andMichael E. McClurken, David Lipson, Robert Luzzi, Arnold E. Oyola,Jonathan E. Wilson, Christopher W.

Maurer, and Roger D. Greeley (all US citizens), for the designation ofthe United States only, on 5 Sep. 2002.

FIELD

This invention relates generally to the field of medical devices,systems and methods for use upon a body during surgery. Moreparticularly, the invention relates to electrosurgical devices, systemsand methods for use upon tissues of a human body during surgery,particularly open surgery and minimally invasive surgery such aslaparoscopic surgery.

BACKGROUND

Electrosurgical devices configured for use with a dry tip use electricalenergy, most commonly radio frequency (RF) energy, to cut tissue or tocauterize blood vessels. During use, a voltage gradient is created atthe tip of the device, thereby inducing current flow and related heatgeneration in the tissue. With sufficiently high levels of electricalenergy, the heat generated is sufficient to cut the tissue and,advantageously, to stop the bleeding from severed blood vessels.

Current dry tip electrosurgical devices can cause the temperature oftissue being treated to rise significantly higher than 100° C.,resulting in tissue desiccation, tissue sticking to the electrodes,tissue perforation, char formation and smoke generation. Peak tissuetemperatures as a result of RF treatment of target tissue can be as highas 320° C., and such high temperatures can be transmitted to adjacenttissue via thermal diffusion. Undesirable results of such transmissionto adjacent tissue include unintended thermal damage to the tissue.

Using saline according to the present invention to couple RF electricalenergy to tissue inhibits such undesirable effects as sticking,desiccation, smoke production and char formation. One key factor isinhibiting tissue desiccation, which occurs when tissue temperatureexceeds 100° C. and all of the intracellular water boils away, leavingthe tissue extremely dry and much less electrically conductive. However,an uncontrolled or abundant flow rate of saline can provide too muchcooling at the electrode/tissue interface. This cooling reduces thetemperature of the target tissue being treated, and the rate at whichtissue thermal coagulation occurs is determined by tissue temperature.This, in turn, can result in longer treatment time to achieve thedesired tissue temperature for treatment of the tissue. Long treatmenttimes are undesirable for surgeons since it is in the best interest ofthe patient, physician and hospital, to perform surgical procedures asquickly as possible.

RF energy delivered to tissue can be unpredictable and often not optimalwhen using general-purpose generators. Most general-purpose RFgenerators have modes for different waveforms (e.g. cut, coagulation, ora blend of these two) and device types (e.g. monopolar, bipolar), aswell as power levels that can be set in watts. However, once thesesettings are chosen, the actual power delivered to tissue and associatedheat generated can vary dramatically over time as tissue impedancechanges over the course of RF treatment. This is because the powerdelivered by most generators is a function of tissue impedance, with thepower ramping down as impedance either decreases toward zero orincreases significantly to several thousand ohms. Current dry tipelectrosurgical devices are not configured to address a change in powerprovided by the generator as tissue impedance changes or the associatedeffect on tissue and rely on the surgeon's expertise to overcome thislimitation.

SUMMARY OF THE INVENTION

In certain embodiments, a system for treating tissue is provided. Thesystem comprises radio frequency power provided from a power source at apower level; an electrically conductive fluid provided from a fluidsource at a fluid flow rate; and an electrosurgical device configured toprovide the radio frequency power and the electrically conductive fluidto the tissue.

In certain embodiments the conductive fluid is an indicator of tissuetemperature. The conductive fluid can relate the tissue temperature toboiling, an amount of boiling, or an onset of boiling of the conductivefluid.

The conductive fluid can cool the tissue or dissipate heat from thetissue. Alternately or additionally, the conductive fluid dissipatesheat from at least one of the tissue and the conductive fluid by aboiling of at least a portion of the fluid.

For other embodiments, at least one of the radio frequency power leveland the flow rate of the conductive fluid is used to effect a boiling ofthe electrically conductive fluid. Furthermore, in some embodiments, theeffect on boiling may comprise at least one of initiating, increasing,decreasing and eliminating boiling of the electrically conductive fluid.

For other embodiments, the electrically conductive fluid functions tolimit the temperature of the tissue at the tissue surface to about aboiling temperature of the electrically conductive fluid.

Generally, the electrically conductive fluid protects the tissue fromdesiccation. In some embodiments, the conductive fluid protects thetissue from desiccation by boiling at least a portion of theelectrically conductive fluid. In other embodiments, the electricallyconductive fluid protects the tissue from desiccation by boiling atleast a portion of the conductive fluid at a temperature below thetemperature of tissue desiccation.

For some embodiments, the electrically conductive fluid is provided tothe tissue at the tissue surface and the radio frequency power is alsoprovided to the tissue at the tissue surface. The radio frequency powerreaches below the tissue surface into the tissue via (through) theelectrically conductive fluid at the tissue surface.

At least one of the radio frequency power level and the conductive fluidflow rate can be adjusted based on a boiling of the conductive fluid.Furthermore, for other embodiments, adjusting at least one of the radiofrequency power level and the conductive fluid flow rate based on aboiling of the conductive fluid comprises one of initiating, increasing,decreasing and eliminating boiling of the electrically conductive fluid.

In certain embodiments, a method for treating tissue is providedcomprising providing radio frequency power at a power level; providingan electrically conductive fluid at a fluid,flow rate; and providing anelectrosurgical device configured to provide the radio frequency powerwith the electrically conductive fluid to the tissue.

Still further, a system for treating tissue is provided, the systemcomprising radio frequency power provided from a power source at a powerlevel; an electrically conductive fluid provided from a fluid source ata fluid flow rate; an electrosurgical device configured to provide theradio frequency power and the conductive fluid to the tissue; and afluid coupling which couples the tissue and the electrosurgical device,the coupling comprising the conductive fluid.

In certain embodiments the fluid coupling is an indicator of tissuetemperature. The fluid coupling can function as an indicator of tissuetemperature by using boiling; an amount of boiling; or an onset ofboiling of the fluid coupling.

For other embodiments, the fluid coupling cools the tissue or dissipatesheat from the tissue. The fluid coupling can dissipate heat from atleast one of the tissue and the fluid coupling by a boiling of at leasta portion of the fluid coupling. For other embodiments, the fluidcoupling can limit the temperature of the tissue at the tissue surfaceto close to a boiling temperature of the fluid coupling.

The fluid coupling can protect the tissue from desiccation. In someembodiments, the fluid coupling protects the tissue from desiccation byboiling at least a portion of the fluid coupling. In other embodiments,the fluid coupling protects the tissue from desiccation by boiling atleast a portion of the fluid coupling at a temperature which protectsthe tissue from desiccation.

For other embodiments, at least one of the radio frequency power leveland the conductive fluid flow rate is used to effect a boiling of thefluid coupling. Furthermore, in some embodiments, the effect on boilingmay be at least one of initiating, increasing, decreasing andeliminating boiling of the fluid coupling.

The conductive fluid can be provided to the tissue at the tissuesurface, and the radio frequency power can also be provided to thetissue at the tissue surface. The radio frequency power can be providedto an area below the tissue surface via (through) the fluid coupling atthe tissue surface.

In certain embodiments, a method for treating tissue is provided, themethod comprising providing radio frequency power at a power level;providing an electrically conductive fluid at a fluid flow rate;providing an electrosurgical device configured to provide the radiofrequency power and the electrically conductive fluid to the tissue; andforming a fluid coupling which couples the tissue and theelectrosurgical device. The fluid coupling comprises conductive fluid.

The fluid coupling can be used as an indicator of tissue temperature.This can be done by boiling; an amount of boiling of the fluid coupling;or an onset of boiling of the fluid coupling.

For some embodiments, the fluid coupling is used to cool the tissue ordissipate heat from the tissue by transferring heat to the fluidcoupling. The fluid coupling can dissipate heat from at least one of thetissue and the fluid coupling by a boiling of at least a portion of thefluid coupling.

For other embodiments, at least one of the radio frequency power leveland the conductive fluid flow rate is adjusted based on a boiling of thefluid coupling. Furthermore, for other embodiments, adjusting at leastone of the radio frequency power level and the conductive fluid flowrate based on a boiling of the fluid coupling comprises one ofinitiating, increasing, decreasing and eliminating boiling of the fluidcoupling.

For other embodiments, the temperature of the tissue at the tissuesurface is limited to about a boiling temperature of the fluid coupling.

For other embodiments, the tissue is protected from desiccation with thefluid coupling. Furthermore, for other embodiments, the tissue isprotected from desiccation with the fluid coupling by a boiling of atleast a portion of the fluid coupling. Furthermore, for otherembodiments, the tissue is protected from desiccation with the fluidcoupling by a boiling of at least a portion of the fluid coupling at atemperature which protects the tissue from desiccation.

The method for treating tissue can further comprise providing theconductive fluid to the tissue at the tissue surface; and providing theradio frequency power to the tissue at the tissue surface and below thetissue surface into the tissue through the fluid coupling.

With regards to specific devices, in certain embodiments a surgicaldevice for treating tissue is provided comprising a handle having aproximal end and a distal end; a shaft extending distally beyond thedistal end of the handle, the shaft having a proximal end and a distalend; an electrode tip, at least a portion of the electrode tip extendingdistally beyond the distal end of the shaft, the electrode tip extendingdistally beyond the distal end of the shaft comprising a spherical endsurface portion and a cylindrical side surface portion, the sphericalend surface portion located distal to the cylindrical side surfaceportion and comprising at least a portion of the distal end surface ofthe surgical device; and a fluid passage directed to provide a fluidtowards the cylindrical side portion of the electrode tip.

In other embodiments, a surgical device for treating tissue is providedcomprising a handle having a proximal end and a distal end; a shaftextending distally beyond the distal end of the handle, the shaft havinga proximal end and a distal end; an electrode tip, at least a portion ofthe electrode tip extending distally beyond the distal end of the shaft,the electrode tip extending distally beyond the distal end of the shaftcomprising a neck portion and an enlarged head portion, the enlargedhead portion located distal to the neck portion and comprising at leasta portion of a distal end surface of the surgical device; and a fluidpassage directed to provide a fluid towards the enlarged head portion ofthe electrode tip.

In still other embodiments, a device for treating tissue is providedcomprising a handle having a proximal end and a distal end; a shaftextending distally beyond the distal end of the handle, the shaft havinga proximal end and a distal end; an electrode tip, the electrode tipcomprising a spherical end surface portion and a cylindrical sidesurface portion, the spherical end surface portion located distal to thecylindrical side surface portion and comprising at least a portion ofthe distal end surface of the device; a fluid passage connectable to afluid source; and a plurality of fluid outlet openings in fluidcommunication with the fluid passage, the fluid outlet openingspositioned to provide a fluid from the fluid source around thecylindrical side surface portion of the electrode tip.

In still other embodiments, a device for treating tissue is providedcomprising a handle having a proximal end and a distal end; a shaftextending distally beyond the distal end of the handle, the shaft havinga proximal end and a distal end; an electrode tip comprising a roundeddistal end surface portion configured to blunt dissect tissue and a sidesurface portion configured to seal tissue from at least one of the flowof bodily fluids and air, the side surface portion having a surface areagreater than the surface area of the distal end surface portion; a fluidpassage connectable to a fluid source; and at least one fluid outletopening in fluid communication with the fluid passage, the fluid outletopening positioned to provide a fluid from the fluid source to the sidesurface portion of the electrode tip and proximal the distal end surfaceportion.

In other embodiments, a device for treating tissue is providedcomprising a first electrode tip spaced from a second electrode tip, thefirst and second electrode tips being connectable to different terminalsof a radio frequency generator to generate electrical current flowtherebetween; at least one fluid passage connectable to a fluid source;at least one fluid outlet opening in fluid communication with the fluidpassage, the fluid outlet opening configured to provide a fluid from thefluid source to at least one of a tissue surface and at least one of thefirst and second electrode tips; and the first and second electrode tipsconfigured to slide over and seal tissue in the presence of a fluidprovided from the fluid outlet opening and an electrical currentprovided from the electrode tips.

Additional methods for treating tissue may also comprise providingtissue having a tissue surface; providing radio frequency power at apower level; providing an electrically conductive fluid at a fluid flowrate; providing an surgical device configured to simultaneously providethe radio frequency power and the electrically conductive fluid totissue; providing the electrically conductive fluid to the tissue at thetissue surface; forming a fluid coupling comprising the electricallyconductive fluid which couples the tissue and the surgical device;providing the radio frequency power to the tissue at the tissue surfaceand below the tissue surface into the tissue through the fluid coupling;sealing the tissue against at least one of the flow of bodily fluids andair by at least one of shrinking collagen and coagulating blood in thetissue; and blunt dissecting the tissue.

In other embodiments, methods for treating tissue may also compriseproviding tissue having a tissue surface; providing radio frequencypower at a power level; providing an electrically conductive fluid at afluid flow rate; providing an surgical device configured tosimultaneously provide the radio frequency power and the electricallyconductive fluid to tissue, the surgical device comprising a firstelectrode tip and a second electrode tip; providing the electricallyconductive fluid to the tissue at the tissue surface; forming a fluidcoupling comprising the electrically conductive fluid which couples thetissue and the surgical device; providing the radio frequency power tothe tissue at the tissue surface and below the tissue surface into thetissue through the fluid coupling; sliding the first electrode tip andthe second electrode tip over the tissue surface; and sealing the tissueagainst at least one of the flow of bodily fluids and air by at leastone of shrinking collagen and coagulating blood in the tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

To better understand and appreciate the invention, refer to thefollowing detailed description in connection with the accompanyingdrawings, hand and computer generated:

FIG. 1 is a block diagram showing one embodiment of a control system ofthe invention, and an electrosurgical device;

FIG. 2 is a schematic graph that describes the relationship between RFpower to tissue (P), flow rate of saline (Q), and tissue temperature (T)when heat conduction to adjacent tissue is considered;

FIG. 3 is schematic graph that describes the relationship between RFpower to tissue (P), flow rate of saline (Q), and tissue temperature (T)when heat conduction to adjacent tissue is neglected;

FIG. 4 is a schematic graph that describes the relationship between RFpower to tissue (P), flow rate of saline (Q), and tissue temperature (T)when the heat required to warm the tissue to the peak temperature (T) 68is considered;

FIG. 5 is a graph showing the relationship of percentage saline boilingand saline flow rate (cc/min) for an exemplary RF generator output of 75watts;

FIG. 6 is a schematic graph that describes the relationship of loadimpedance (Z, in ohms) and generator output power (P, in watts), for anexemplary generator output of 75 watts in a bipolar mode;

FIG. 7 is a schematic graph that describes the relationship of time (t,in seconds) and tissue impedance (Z, in ohms) after RF activation;

FIG. 8 is a schematic perspective view of a cannula which may be usedwith an electrosurgical device according to the present inventions

FIG. 9 is a schematic exploded perspective view of an assembly of anelectrosurgical device according to the present invention;

FIG. 10 is a schematic longitudinal cross-sectional side view of the tipand shaft of the device of FIG. 9 taken along line 10-10 of FIG. 12;

FIG. 11 is a schematic close-up longitudinal cross-sectional side viewof the tip portion of the device bounded by circle 45 shown in FIG. 10taken along line 10-10 of FIG. 12;

FIG. 12 is a schematic distal end view of the tip portion of the devicebounded by circle 45 shown in FIG. 10;

FIG. 13 is a schematic side view of the of the tip and shaft of thedevice of FIG. 9 with a fluid coupling to a tissue surface of tissue;

FIG. 14 is a schematic close-up cross-sectional side view of analternative tip portion;

FIG. 15 is a schematic close-up section side view of the tip portion ofFIG. 14 taken along line 15-15 of FIG. 14;

FIG. 16 is a schematic close-up cross-sectional side view of the tipportion of FIG. 14 disposed in a tissue crevice;

FIG. 17 is a schematic graph of impedance Z versus time t showingchanges in impedance represented by impedance spikes;

FIG. 18 is a schematic graph of the impedance Z versus boiling of fluid%;

FIG. 19 is schematic close-up cross-sectional view of the sleeve takenalong line 19-19 of FIG. 15;

FIG. 20 is a schematic close-up perspective view of an alternative tipportion;

FIG. 21 is a schematic close-up section side view of the tip portion ofFIG. 20 taken along line 21-21 of FIG. 20;

FIG. 22 is a schematic close-up cross-sectional side view of the tipportion of FIG. 20 disposed in a tissue crevice;

FIG. 23 is a schematic close-up front perspective view of the electrodefor the tip portion of FIG. 20;

FIG. 24 is a schematic close-up rear perspective view of the electrodefor the tip portion of FIG. 20;

FIG. 25 is a schematic close up cross-sectional view of a porouselectrode with recesses;

FIG. 26 is schematic close up cross-sectional view of an electrode withsemi-circular recesses;

FIG. 27 is schematic close up cross-sectional view of an electrode withV-shaped recesses;

FIG. 28 is schematic close up cross-sectional view of an electrode withU-shaped recesses;

FIG. 29 is a schematic close-up perspective view of an alternative tipportion;

FIG. 30 is a schematic close-up section side view of the tip portion ofFIG. 29 taken along line 30-30 of FIG. 29;

FIG. 31 is a schematic close-up front perspective view of the electrodefor the tip portion of FIG. 29;

FIG. 32 is a schematic close-up rear perspective view of the electrodefor the tip portion of FIG. 29;

FIG. 33 is a schematic close-up perspective view of an alternative tipportion;

FIG. 34 is a schematic close-up section side view of the tip portion ofFIG. 33 taken along line 34-34 of FIG. 33;

FIG. 35 is a schematic close-up front perspective view of the electrodefor the tip portion of FIG. 33;

FIG. 36 is a schematic close-up rear perspective view of the electrodefor the tip portion of FIG. 33;

FIG. 37 is a schematic close-up perspective view of an alternative tipportion;

FIG. 38 is a schematic close-up section side view of the tip portion ofFIG. 37 taken along line 38-38 of FIG. 37;

FIG. 39 is a schematic close-up perspective view of an alternative tipportion;

FIG. 40 is a schematic close-up section side view of the tip portion ofFIG. 39 taken along line 40-40 of FIG. 39;

FIG. 41 is a schematic close-up front posterior perspective view of theelectrode for the tip portion of FIG. 39;

FIG. 42 is a schematic close-up front anterior perspective view of theelectrode for the tip portion of FIG. 39;

FIG. 43 is a schematic side view of the tip portion of FIG. 39 with afluid coupling to a tissue surface of tissue;

FIG. 44 is a schematic front view of the tip portion of FIG. 39 with afluid coupling to a tissue surface of tissue;

FIG. 45 is a schematic side view of the tip portion of FIG. 39 with afluid coupling to a tissue surface of tissue;

FIG. 46 is a schematic exploded perspective view of an assembly of analternative electrosurgical device according to the present invention;

FIG. 46A is a schematic close-up cross-sectional side view of the tipportions of FIG. 46 showing electrodes having a porous structure;

FIG. 47 is a schematic close-up cross-sectional side view of the tipportions of FIG. 46 assembled with a fluid coupling to a tissue surfaceof tissue;

FIG. 48 is a schematic close-up cross-sectional side view of the tipportions of FIG. 46 assembled with an alternative fluid coupling to atissue surface of tissue;

FIG. 49 is a schematic exploded perspective view of an assembly of analternative electrosurgical device according to the present invention;

FIG. 50 is a schematic close-up cross-sectional side view of the tipportions of FIG. 49 assembled with a fluid coupling to a tissue surfaceof tissue;

FIG. 51 is a schematic exploded perspective view of an assembly of analternative electrosurgical device according to the present invention;

FIG. 52 is a schematic close-up perspective side view of a distal endportion of the device of FIG. 51;

FIG. 53 is a schematic close-up cross-sectional side view of a distalend portion of the device of FIG. 51 assembled with a fluid coupling toa tissue surface of tissue;

FIG. 54 is a schematic perspective view of an alternativeelectrosurgical device according to the present invention;

FIG. 55 is a schematic perspective view of an alternativeelectrosurgical device according to the present invention;

FIG. 56 is a schematic close-up perspective view of the arms of thedevice of FIG. 55;

FIG. 57 is a schematic close-up perspective view of a distal end portionof the device of FIG. 55;

FIG. 58 is a schematic close-up perspective view of a distal end portionof the device of FIG. 55;

FIG. 59 is a schematic perspective view of an alternativeelectrosurgical device according to the present invention;

FIG. 60 is a schematic close-up perspective view of the arms of thedevice of FIG. 59;

FIG. 61 is a schematic close-up perspective view of a distal end portionof the device of FIG. 59;

FIG. 62 is a schematic close-up perspective view of a distal end portionof the device of FIG. 59;

FIG. 63 is a schematic close-up perspective view of a distal end portionof an alternative electrosurgical device according to the presentinvention;

FIG. 64 is a schematic close-up perspective view of a distal end portionof the device of FIG. 63 with tissue;

FIG. 65 is a schematic close-up perspective view of the arms of analternative electrosurgical device according to the present invention;

FIG. 66 is a schematic close-up perspective view of a distal end portionof the arms of the device of FIG. 65 with the collar removed;

FIG. 67 is a schematic close-up perspective view of a distal end portionof the device of FIG. 65;

FIG. 68 is a schematic close-up perspective view of a distal end portionof the device of FIG. 65 with one arm removed;

FIG. 69 is a schematic close-up perspective view of the collar of thedevice of FIG. 65;

FIG. 70 is a schematic close-up perspective view of a distal end portionof an alternative electrosurgical device according to the presentinvention;

FIG. 71 is a schematic close-up perspective view of a distal end portionof one of the arms of the device of FIG. 70;

FIG. 72 is a schematic close-up perspective view of a distal end portionof an alternative electrosurgical device according to the presentinvention;

FIG. 73 is a schematic close-up side view of a distal end portion of thedevice of FIG. 72;

FIG. 74 is a schematic perspective view of an alternativeelectrosurgical device according to the present invention;

FIG. 75 is a schematic perspective view of a handle portion of thedevice of FIG. 74 assembled with various components;

FIG. 76 is a schematic close-up side view of a portion of the assemblyof FIG. 75;

FIG. 77 is a schematic close-up side view of a portion of the assemblyof FIG. 75;

FIG. 78 is a schematic partial cross-sectional front perspective view ofthe electrical connections for the device of FIG. 74;

FIG. 79 is schematic partial cross-sectional rear perspective view ofthe electrical connections for the device of FIG. 74;

FIG. 80 is a schematic perspective view of an alternativeelectrosurgical device according to the present invention;

FIG. 81 is a schematic side view of a handle portion of the device ofFIG. 80 assembled with various components;

FIG. 82 is a schematic perspective view of an alternativeelectrosurgical device according to the present invention;

FIG. 83 is a schematic perspective view of a handle portion of thedevice of FIG. 82 assembled with various components;

FIG. 84 is a schematic side view of a handle portion of the device ofFIG. 82 assembled with various components;

FIG. 85 is a schematic side view of a handle portion of the device ofFIG. 82 assembled with various components;

FIG. 86 is a schematic side view of a handle portion of the device ofFIG. 82 assembled with various components;

FIG. 87 is a schematic perspective view of an alternativeelectrosurgical device according to the present invention;

FIG. 88 is a schematic perspective view of a handle portion of thedevice of FIG. 87;

FIG. 89 is a schematic side view of a handle portion of the device ofFIG. 87;

FIG. 90 is a schematic perspective view of a handle portion analternative electrosurgical device according to the present invention;and

FIG. 91 is a schematic side view of the handle portion of FIG. 90.

FIG. 92 is a schematic perspective view of a handle portion analternative electrosurgical device according to the present invention;and

FIG. 93 is a schematic side view of the handle portion of FIG. 92.

DETAILED DESCRIPTION

Throughout the present description, like reference numerals and lettersindicate corresponding structure throughout the several views, and suchcorresponding structure need not be separately discussed. Furthermore,any particular feature(s) of a particular exemplary embodiment may beequally applied to any other exemplary embodiment(s) of thisspecification as suitable. In other words, features between the variousexemplary embodiments described herein are interchangeable as suitable,and not exclusive.

The invention provides devices, systems and methods that preferablyimprove control of tissue temperature at a tissue treatment site duringa medical procedure. The invention is particularly useful duringsurgical procedures upon tissues of the body, where it is desirable tocoagulate and shrink tissue, to occlude lumens of blood vessels (e.g.arteries, veins), airways (e.g. bronchi, bronchioles), bile ducts andlymphatic ducts.

The invention includes electrosurgical procedures, which preferablyutilize RF power and electrically conductive fluid, to treat tissue.Preferably, a desired tissue temperature range is achieved by adjustingparameters, such as conductive fluid flow rate, that affect thetemperature at the tissue/electrode interface. Preferably, the deviceachieves a desired tissue temperature by utilizing a desired percentageboiling of the conductive solution at the tissue/electrode interface.

In one embodiment, the invention provides a control device, the devicecomprising a flow rate controller that receives a signal indicatingpower applied to the system, and adjusts the flow rate of conductivefluid from a fluid source to an electrosurgical device. The inventionalso contemplates a control system comprising a flow rate controller, ameasurement device that measures power applied to the system, and a pumpthat provides fluid at a selected flow rate.

The invention will be discussed generally with reference to FIG. 1. FIG.1 shows a block diagram of one exemplary embodiment of a system of theinvention. Preferably, as shown in FIG. 1, an electrically conductivefluid 24 is provided from a fluid source 1 through a fluid line 2 to apump 3, which has an outlet fluid line 4 a that is connected as an inputfluid line 4 b, to electrosurgical device 5. In a preferred embodiment,the outlet fluid line 4 a and the input fluid line 4 b are flexible andare made from a polymeric material, such as polyvinylchloride (PVC) orpolyolefin (e.g. polypropylene, polyethylene) and the conductive fluidcomprises a saline solution. More preferably, the saline comprisessterile, and even more preferably, normal saline. Although thedescription herein will specifically describe the use of saline as thefluid 24, other electrically conductive fluids, as well asnon-conductive fluids, can be used in accordance with the invention.

For example, in addition to the conductive fluid comprising physiologicsaline (also known as “normal” saline, isotonic saline or 0.9% sodiumchloride (NaCl) solution), the conductive fluid may comprise hypertonicsaline solution, hypotonic saline solution, Ringers solution (aphysiologic solution of distilled water containing specified amounts ofsodium chloride, calcium chloride, and potassium chloride), lactatedRinger's solution (a crystalloid electrolyte sterile solution ofdistilled water containing specified amounts of calcium chloride,potassium chloride, sodium chloride, and sodium lactate), Locke-Ringer'ssolution (a buffered isotonic solution of distilled water containingspecified amounts of sodium chloride, potassium chloride, calciumchloride, sodium bicarbonate, magnesium chloride, and dextrose), or anyother electrolyte solution. In other words, a solution that conductselectricity via an electrolyte, a substance (salt, acid or base) thatdissociates into electrically charged ions when dissolved in a solvent,such as water, resulting solution comprising an ionic conductor.

While a conductive fluid is preferred, as will become more apparent withfurther reading of this specification, the fluid 24 may also comprise anelectrically non-conductive fluid. The use of a non-conductive fluid isless preferred to that of a conductive fluid as the non-conductive fluiddoes not conduct electricity. However, the use of a non-conductive fluidstill provides certain advantages over the use of a dry electrodeincluding, for example, reduced occurrence of tissue sticking to theelectrode of the device 5 and cooling of the electrode and/or tissue.Therefore, it is also within the scope of the invention to include theuse of a non-conducting fluid, such as, for example, dionized water.

Returning to FIG. 1, energy to heat tissue is provided from energysource, such as an electrical generator 6 which preferably provides RFalternating current energy via a cable 7 to energy source outputmeasurement device, such as a power measurement device 8 that measuresthe RF alternating current electrical power. In one exemplaryembodiment, preferably the power measurement device 8 does not turn thepower off or on, or alter the power in any way. A power switch 15connected to the generator 6 is preferably provided by the generatormanufacturer and is used to turn the generator 6 on and off. The powerswitch 15 can comprise any switch to turn the power on and off, and iscommonly provided in the form of a footswitch or other easily operatedswitch, such as a switch 15 a mounted on the electrosurgical device 5.The power switch 15 or 15 a may also function as a manually activateddevice for increasing or decreasing the rate of energy provided from thesurgical device 5. Alternatively, internal circuitry and othercomponents of the generator 6 may be used for automatically increasingor decreasing the rate of energy provided from the surgical device 5. Acable 9 preferably carries RF energy from the power measurement device 8to the electrosurgical device 5. Power, or any other energy sourceoutput, is preferably measured before it reaches the electrosurgicaldevice 5.

For the situation where capacitation and induction effects arenegligibly small, from Ohm's law, power P, or the rate of energydelivery (e.g. joules/sec), may be expressed by the product of currenttimes voltage (i.e. I×V), the current squared times resistance (i.e.I²×R), or the voltage squared divided by the resistance, (i.e. V²/R);where the current I may be measured in amperes, the voltage V may bemeasured in volts, the electrical resistance R may be measured in ohms,and the power P may be measured in watts (joules/sec). Given that powerP is a function of current I, voltage V, and resistance R as indicatedabove, it should be understood, that a change in power P is reflectiveof a change in at least one of the input variables. Thus, one mayalternatively measure changes in such input variables themselves, ratherthan power P directly, with such changes in the input variablesmathematically corresponding to a changes in power P as indicated above.

As to the frequency of the RF electrical energy, it is preferablyprovided within a frequency band (i.e. a continuous range of frequenciesextending between two limiting frequencies) in the range between andincluding about 9 kHz (kilohertz) to 300 GHz (gigahertz). Morepreferably, the RF energy is provided within a frequency band in therange between and including about 50 kHz (kilohertz) to 50 MHz(megahertz). Even more preferably, the RF energy is provided within afrequency band in the range between and including about 200 kHz(kilohertz) to 2 MHz (megahertz). Most preferably, RF energy is providedwithin a frequency band in the range between and including about 400 kHz(kilohertz) to 600 kHz (kilohertz). Further, it should also beunderstood that, for any frequency band identified above, the range offrequencies may be further narrowed in increments of 1 (one) hertzanywhere between the lower and upper limiting frequencies.

While RF electrical energy is preferred, it should be understood thatthe electrical energy (i.e., energy made available by the flow ofelectric charge, typically through a conductor or by self-propagatingwaves) may comprise any frequency of the electromagnetic spectrum (i.e.the entire range of radiation extending in frequency from 10²³ hertz to0 hertz) and including, but not limited to, gamma rays, x-rays,ultraviolet radiation, visible light, infrared radiation, microwaves,and any combinations thereof.

With respect to the use of electrical energy, heating of the tissue ispreferably performed by means of resistance heating. In other words,increasing the temperature of the tissue as a result of electric currentflow through the tissue, with the electrical energy being absorbed fromthe voltage and transformed into thermal energy (i.e. heat) viaaccelerated movement of ions as a function of the tissue's electricalresistance.

Heating with electrical energy may also be performed by means ofdielectric heating (capacitation). In other words, increasing thetemperature of the tissue through the dissipation of electrical energyas a result of internal dielectric loss when the tissue is placed in avarying electric field, such as a high-frequency (e.g. microwave),alternating electromagnetic field. Dielectric loss is the electricalenergy lost as heat in the polarization process in the presence of theapplied electric field. In the case of an alternating current field, theenergy is absorbed from the alternating current voltage and converted toheat during the polarization of the molecules.

However, it should be understood that energy provided to heat the tissuemay comprise surgical devices other than electrosurgical devices, energysources other than generators, energy forms other than electrical energyand mechanisms other than resistance heating. For example, providingthermal energy to the tissue from energy source with a difference (e.g.higher) in temperature. Such may be provided, for example, to the tissuefrom a heated device, which heats tissue through direct contact with theenergy source (conduction), heats through contact with a flowing fluid(convection), or from a remote heat source (radiation).

Also, for example, providing energy to the tissue may be provided viamechanical energy which is transformed into thermal energy viaaccelerated movement of the molecules, such as by mechanical vibrationprovided, for example, by energy source such as a transducer containinga piezoelectric substance (e.g., a quartz-crystal oscillator) thatconverts high-frequency electric current into vibrating ultrasonic waveswhich may be used by, for example, an ultrasonic surgical device.

Also, for example, providing energy to the tissue may be provided viaradiant energy (i.e. energy which is transmitted by radiation/waves)which is transformed into thermal energy via absorption of the radiantenergy by the tissue. Preferably the radiation/waves compriseelectromagnetic radiation/waves which include, but is not limited to,radio waves, microwaves, infrared radiation, visible light radiation,ultraviolet radiation, x-rays and gamma rays. More preferably, suchradiant energy comprises energy with a frequency of 3×10¹¹ hertz to3×10¹⁶ hertz (i.e. the infrared, visible, and ultraviolet frequencybands of the electromagnetic spectrum). Also preferably theelectromagnetic waves are coherent and the electromagnetic radiation isemitted from energy source such as a laser device.

A flow rate controller 11 preferably includes a selection switch 12 thatcan be set to achieve desired levels of percentage fluid boiling (forexample, 100%, 98%, 80% boiling). Preferably, the flow rate controller11 receives an input signal 10 from the power measurement device 8 andcalculates an appropriate mathematically predetermined fluid flow ratebased on percentage boiling indicated by the selection switch 12. In apreferred embodiment, a fluid switch 13 is provided so that the fluidsystem can be primed (e.g. air eliminated) before turning the generator6 on. The output signal 16 of the flow rate controller 11 is preferablysent to the pump 3 motor to regulate the flow rate of conductive fluid,and thereby provide an appropriate fluid flow rate which corresponds tothe amount of power being delivered.

In one exemplary embodiment, the invention comprises a flow ratecontroller 11 that is configured and arranged to be connected to asource of RF power (e.g. generator 6), and a source of fluid (e.g. fluidsource 1), for example, a source of conductive fluid. The device of theinvention receives information about the level of RF power applied to anelectrosurgical device 5, and adjusts the flow rate of the fluid 24 tothe electrosurgical device 5, thereby controlling temperature at thetissue treatment site.

In another exemplary embodiment, elements of the system are physicallyincluded together in one electronic enclosure. One such embodiment isshown by enclosure within the outline box 14 of FIG. 1. In theillustrated embodiment, the pump 3, flow rate controller 11, and powermeasurement device 8 are enclosed within an enclosure, and theseelements are connected through electrical connections to allow signal 10to pass from the power measurement device 8 to the flow rate controller11, and signal 16 to pass from the flow rate controller 11 to the pump3. Other elements of a system can also be included within one enclosure,depending upon such factors as the desired application of the system,and the requirements of the user.

The pump 3 can be any suitable pump used in surgical procedures toprovide saline or other fluid at a desired flow rate. Preferably, thepump 3 comprises a peristaltic pump. With a rotary peristaltic pump,typically a fluid 24 is conveyed within the confines of a flexible tube(e.g. 4 a) by waves of contraction placed externally on the tube whichare produced mechanically, typically by rotating rollers which squeezethe flexible tubing against a support intermittently. Alternatively,with a linear peristaltic pump, typically a fluid 24 is conveyed withinthe confines of a flexible tube by waves of contraction placedexternally on the tube which are produced mechanically, typically by aseries of compression fingers or pads which squeeze the flexible tubingagainst a support sequentially. Peristaltic pumps are generallypreferred for use as the electromechanical force mechanism (e.g. rollersdriven by electric motor) does not make contact the fluid 24, thusreducing the likelihood of inadvertent contamination.

Alternatively, pump 3 can be a “syringe pump”, with a built-in fluidsupply. With such a pump, typically a filled syringe is located on anelectromechanical force mechanism (e.g. ram driven by electric motor)which acts on the plunger of the syringe to force delivery of the fluid24 contained therein. Alternatively, the syringe pump may comprise adouble-acting syringe pump with two syringes such that they can drawsaline from a reservoir (e.g. of fluid source 1), either simultaneouslyor intermittently. With a double acting syringe pump, the pumpingmechanism is generally capable of both infusion and withdrawal.Typically, while fluid 24 is being expelled from one syringe, the othersyringe is receiving fluid 24 therein from a separate reservoir. In thismanner, the delivery of fluid 24 remains continuous and uninterrupted asthe syringes function in series. Alternatively, it should be understoodthat a multiple syringe pump with two syringes, or any number ofsyringes, may be used in accordance with the invention.

Furthermore, fluid 24, such as conductive fluid, can also be providedfrom an intravenous (IV) bag full of saline (e.g. of fluid source 1)that flows under the influence (i.e. force) of gravity. In such amanner, the fluid 24 may flow directly to the electrosurgical device 5,or first to the pump 3 located there between. Alternatively, fluid 24from a fluid source 1 such as an IV bag can be provided through an IVflow controller that may provide a desired flow rate by adjusting thecross sectional area of a flow orifice (e.g. lumen of the connectivetubing with the electrosurgical device 5) while sensing the flow ratewith a sensor such as an optical drop counter. Furthermore, fluid 24from a fluid source 1 such as an IV bag an be provided through amanually or automatically activated device such as a flow controller,such as a roller clamp, which also adjusts the cross sectional area of aflow orifice and may be adjusted manually by, for example, the user ofthe device in response to their visual observation (e.g. fluid boiling)at the tissue treatment site or a pump.

Similar pumps can be used in connection with the invention, and theillustrated embodiments are exemplary only. The precise configuration ofthe pump 3 is not critical to the invention. For example, pump 3 mayinclude other types of infusion and withdrawal pumps. Furthermore, pump3 may comprise pumps which may be categorized as piston pumps, rotaryvane pumps (e.g. axial impeller, centrifugal impeller), cartridge pumpsand diaphragm pumps. In some embodiments, the pump 3 can be substitutedwith any type of flow controller, such as a manual roller clamp used inconjunction with an IV bag, or combined with the flow controller toallow the user to control the flow rate of conductive fluid to thedevice. Alternatively, a valve configuration can be substituted for pump3.

Furthermore, similar configurations of the system can be used inconnection with the invention, and the illustrated embodiments areexemplary only. For example, the fluid source 1 pump 3, generator 6,power measurement device 8 or flow rate controller 11, or any othercomponents of the system not expressly recited above, may comprise aportion of the electrosurgical device 5. For example, in one exemplaryembodiment the fluid source 1 may comprise a compartment of theelectrosurgical device 5 which contains fluid 24, as indicated atreference character 1 a. In another exemplary embodiment, thecompartment may be detachably connected to the electrosurgical device 5,such as a canister which may be attached via threaded engagement withthe device 5. In yet another exemplary embodiment, the compartment maybe configured to hold a pre-filled cartridge of fluid 24, rather thanthe fluid directly.

Also for example, with regards to alternative for the generator 6, anenergy source, such as a direct current (DC) battery used in conjunctionwith inverter circuitry and a transformer to produce alternating currentat a particular frequency, may comprise a portion of the electrosurgicaldevice 5, as indicated at reference character 6 a. In one embodiment thebattery element of the energy source may comprise a rechargeablebattery. In yet another exemplary embodiment, the battery element may bedetachably connected to the electrosurgical device 5, such as forrecharging. The components of the system will now be described infurther detail. From the specification, it should be clear that any useof the terms “distal” and “proximal” are made in reference from the userof the device, and not the patient.

The flow rate controller 11 controls the rate of flow from the fluidsource 1. Preferably, the rate of fluid flow from the fluid source 1 isbased upon the amount of RF power provided from the generator 6 to theelectrosurgical device 5. In other words, as shown in FIG. 2, preferablythere is a relationship between the rate of fluid flow Q and the RFpower P indicated by the Y- and X-axes of the schematic graph,respectively. More precisely, as shown in FIG. 2, the relationshipbetween the rate of fluid flow Q and RF power P may be expressed as adirect, linear relationship. The flow rate Q of conductive fluid 24,such as saline, interacts with the RF power P and various modes of heattransfer away from the target tissue, as described herein.

Throughout this disclosure, when the terms “boiling point of saline”,“vaporization point of saline”, and variations thereof are used, what isactually referenced for explanation purposes, is the boiling point ofthe water (i.e. 100° C.) in the saline solution given that thedifference between the boiling point of normal saline (about 100.16° C.)and the boiling point of water is negligible.

FIG. 2 shows a schematic graph that describes the relationship betweenthe flow rate of saline, RF power to tissue, and regimes of boiling asdetailed below. Based on a simple one-dimensional lumped parameter modelof the heat transfer, the peak tissue temperature can be estimated, andonce tissue temperature is estimated, it follows directly whether it ishot enough to boil saline. The total RF electrical power P that isconverted into heat can be defined as:P=ΔT/R+ρc _(ρ) Q ₁ ΔT+ρQ _(b) h _(v)   (1)where P=the total RF electrical power that is converted into heat.

Conduction. The term [≢T/R] in equation (1) is heat conducted toadjacent tissue, represented as 70 in FIG. 2, where:

-   -   ΔT=(T−T_(∞)) the difference in temperature between the peak        tissue temperature (T) and the normal temperature (T_(∞)) of the        body tissue (° C.). Normal temperature of the body tissue is        generally 37° C.; and    -   R=Thermal resistance of surrounding tissue, the ratio of the        temperature difference to the heat flow (° C./watt).

This thermal resistance can be estimated from published data gathered inexperiments on human tissue (see for example, Phipps, J. H.,“Thermometry studies with bipolar diathermy during hysterectomy,”Gynaecological Endoscopy, 3:5-7 (1994)). As described by Phipps,Kleppinger bipolar forceps were used with an RF power of 50 watts, andthe peak tissue temperature reached 320° C. For example, using theenergy balance of equation (1), and assuming all the RF heat put intotissue is conducted away, then R can be estimated:R=ΔT/P=(320−37)/50=5.7≈6° C./watt

However, it is undesirable to allow the tissue temperature to reach 320°C., since tissue will become desiccated. At a temperature of 320° C.,the fluid contained in the tissue is typically boiled away, resulting inthe undesirable tissue effects described herein. Rather, it is preferredto keep the peak tissue temperature at no more than about 100° C. toinhibit desiccation of the tissue. Assuming that saline boils at about100° C., the first term in equation (1) (ΔT/R) is equal to(100−37)/6=10.5 watts. Thus, based on this example, the maximum amountof heat conducted to adjacent tissue without any significant risk oftissue desiccation is 10.5 watts.

Referring to FIG. 2, RF power to tissue is represented on the X-axis asP (watts) and flow rate of saline (cc/min) is represented on the Y-axisas Q. When the flow rate of saline equals zero (Q=0), there is an“offset” RF power that shifts the origin of the sloped lines 76, 78, and80 to the right. This offset is the heat conducted to adjacent tissue.For example, using the calculation above for bipolar forceps, thisoffset RF power is about 10.5 watts. If the power is increased abovethis level with no saline flow, the peak tissue temperature can risewell above 100° C., resulting in tissue desiccation from the boiling offof water in the cells of the tissue.

Convection. The second term [ρc_(ρ)Q₁ΔT] in equation (1) is heat used towarm up the flow of saline without boiling the saline, represented as 72in FIG. 2, where:

-   -   ρ=Density of the saline fluid that gets hot but does not boil        (approximately 1.0 gm/cm³);    -   c_(ρ)=Specific heat of the saline (approximately 4.1        watt-sec/gm-° C.);    -   Q₁=Flow rate of the saline that is heated (cm³/sec); and    -   ΔT=Temperature rise of the saline. Assuming that the saline is        heated to body temperature before it gets to the electrode, and        that the peak saline temperature-is similar to the peak tissue        temperature, this is the same ΔT as for the conduction        calculation above.

The onset of boiling can be predicted using equation (1) with the lastterm on the right set to zero (no boiling) (ρQ_(b)h_(v)=0), and solvingequation (1) for Q₁ leads to:Q ₁ =[P−ΔT/R]/ρc _(ρ) ΔT   (2)

This equation defines the line shown in FIG. 2 as the line of onset ofboiling 76.

Boiling. The third term [ρQ_(b)h_(v)] in equation (1) relates to heatthat goes into converting the water in liquid saline to water vapor, andis represented as 74 in FIG. 2, where:

-   -   Q_(b)=Flow rate of saline that boils (cm³/sec); and    -   h_(v)=Heat of vaporization of saline (approximately 2,000        watt-sec/gm).

A flow rate of only 1 cc/min will absorb a significant amount of heat ifit is completely boiled, or about ρQ_(b)h_(v)=(1) (1/60) (2,000)=33.3watts. The heat needed to warm this flow rate from body temperature to100° C. is much less, or ρc_(ρ)Q₁ΔT=(1) (4.1) (1/60) (100−37)=4.3 watts.In other words, the most significant factor contributing to heattransfer from a wet electrode device can be fractional boiling. Thepresent invention recognizes this fact and exploits it.

Fractional boiling can be described by equation (3) below:

$\begin{matrix}{Q_{1} = \frac{\left\{ {P - {\Delta\;{T/R}}} \right\}}{\left\{ {{\rho\; c_{p}\Delta\; T} + {\rho\; h_{v}{Q_{b}/Q_{l}}}} \right\}}} & (3)\end{matrix}$

If the ratio of Q_(b)/Q₁ is 0.50 this is the 50% boiling line 78 shownin FIG. 2. If the ratio is 1.0 this is the 100% boiling line 80 shown inFIG. 2.

As indicated previously in the specification, using a fluid to coupleenergy to tissue inhibits such undesirable effects as sticking,desiccation, smoke production and char formation, and that one keyfactor is inhibiting tissue desiccation, which occur if the tissuetemperature exceeds 100° C. and all the intracellular water boils away,leaving the tissue extremely dry and much less electrically conductive.

As shown in FIG. 2, one control strategy or mechanism which can beemployed for the electrosurgical device 5 is to adjust the power P andflow rate Q 5 such that the power P used at a corresponding flow rate Qis equal to or less than the power P required to boil 100% of the fluidand does not exceed the power P required to boil 100% of the fluid. Inother words, this control strategy targets using the electrosurgicaldevice 5 in the regions of FIG. 2 identified as T<100° C. and T=100° C.,and includes the 100% boiling line 80. Stated another way, this control10 strategy targets not using the electrosurgical device 5 only in theregion of FIG. 2 identified as T>>100° C.

Another control strategy that can be used for the electrosurgical device5 is to operate the device 5 in the region T<100° C., but at high enoughtemperature to shrink tissue containing Type I collagen (e.g., walls ofblood vessels, bronchi, bile ducts, etc.), which shrinks when exposed toabout 85° C. for an exposure time of 0.01 seconds, or when exposed toabout 65° C. for an exposure time of 15 minutes. An exemplary targettemperature/time for tissue shrinkage is about 75° C. with an exposuretime of about 1 second. As discussed herein, a determination of the highend of the scale (i.e., when the fluid reaches 100° C.) can be made bythe phase change in the fluid from liquid to vapor. However, adetermination at the low end of the scale (e.g., when the fluid reaches,for example, 75° C. for 1 second) requires a different mechanism as thetemperature of the fluid is below the boiling temperature and no suchphase change is apparent. In order to determine when the fluid reaches atemperature that will facilitate tissue shrinkage, for example 75° C., athermochromic material, such as a thermochromic dye (e.g., leuco dye),may be added to the fluid. The dye can be formulated to provide a firstpredetermined color to the fluid at temperatures below a thresholdtemperature, such as 75° C., then, upon heating above 75° C., the dyeprovides a second color, such as clear, thus turning the fluid clear(i.e. no color or reduction in color). This color change may be gradual,incremental, or instant. Thus, a change in the color of the fluid, froma first color to a second color (or lack thereof) provides a visualindication to the user of the electrosurgical device 5 as to when athreshold fluid temperature below boiling has been achieved.Thermochromic dyes are available, for example, from Color ChangeCorporation, 1740 Cortland Court, Unit A, Addison, Ill. 60101.

It is also noted that the above mechanism (i.e., a change in the colorof the fluid due to a dye) may also be used to detect when the fluidreaches a temperature which will facilitate tissue necrosis; thisgenerally varies from about 60° C. for an exposure time of 0.01 secondsand decreasing to about 45° C. for an exposure time of 15 minutes. Anexemplary target temperature/time for tissue necrosis is about 55° C.for an exposure time of about 1 second.

In order to reduce coagulation time, use of the electrosurgical device 5in the region T=100° C. of FIG. 2 is preferable to use of theelectrosurgical device 5 in the region T<100° C. Consequently, as shownin FIG. 2, another control strategy which may be employed for theelectrosurgical device 5 is to adjust the power P and flow rate Q suchthat the power P used at a corresponding flow rate Q is equal to or morethan the power P required to initiate boiling of the fluid, but stillless than the power P required to boil 100% of the fluid. In otherwords, this control strategy targets using the electrosurgical device 5in the region of FIG. 2 identified as T=100° C., and includes the linesof the onset of boiling 76 and 100% boiling line 80. Stated another way,this control strategy targets use using the electrosurgical device 5 onor between the lines of the onset of boiling 76 and 100% boiling line80, and not using the electrosurgical device 5 in the regions of FIG. 2identified as T<100° C. and T>>100° C.

For consistent tissue effect, it is desirable to control the saline flowrate so that it is always on a “line of constant % boiling” as, forexample, the line of the onset of boiling 76 or the 100% boiling line 80or any line of constant % boiling located in between (e.g. 50% boilingline 78) as shown in FIG. 2. Consequently, another control strategy thatcan be used for the electrosurgical device 5 is to adjust power P andflow rate Q such that the power P used at a corresponding flow rate Qtargets a line of constant % boiling.

It should be noted, from the preceding equations, that the slope of anyline of constant % boiling is known. For example, for the line of theonset of boiling 76, the slope of the line is given by (ρc_(p)ΔT), whilethe slope of the 100% boiling line 80 is given by 1/(ρc_(p)ΔT+ρh_(v)).As for the 50% boiling line 78, for example, the slope is given by1/(ρc_(p)ΔT+ρh_(v)0.5).

If, upon application of the electrosurgical device 5 to the tissue,boiling of the fluid is not detected, such indicates that thetemperature is less than 100° C. as indicated in the area of FIG. 2, andthe flow rate Q must be decreased to initiate boiling. The flow rate Qmay then decreased until boiling of the fluid is first detected, atwhich time the line of the onset of boiling 76 is transgressed and thepoint of transgression on the line 76 is determined. From thedetermination of a point on the line of the onset of boiling 76 for aparticular power P and flow rate Q, 35 and the known slope of the line76 as outlined above (i.e. 1/ρc_(p)ΔT), it is also possible to determinethe heat conducted to adjacent tissue 70.

Conversely, if upon application of the electrosurgical device 5 to thetissue, boiling of the fluid is detected, such indicates that thetemperature is approximately equal to 100° C. as indicated in the areasof FIG. 2, and the flow rate Q must be increased to reduce boiling untilboiling stops, at which time the line of the onset of boiling 76 istransgressed and the point of transgression on the line 76 determined.As with above, from the determination of a point on the line of theonset of boiling 76 for a particular power P and flow rate Q, and theknown slope of the line 76, it is also possible to determine the heatconducted to adjacent tissue 70.

With regards to the detection of boiling of the fluid, such may bephysically detected by the user (e.g. visually by the naked eye) of theelectrosurgical device 5 in the form of either bubbles or steam evolvingfrom the fluid coupling at the electrode/tissue interface.Alternatively, such a phase change (i.e. from liquid to vapor orvice-versa) may be measured by a sensor which preferably senses eitheran absolute change (e.g. existence or non-existence of boiling withbinary response such as yes or no) or a change in a physical quantity orintensity and converts the change into a useful input signal for aninformation-gathering system. For example, the phase change associatedwith the onset of boiling may be detected by a pressure sensor, such asa pressure transducer, located on the electrosurgical device 5.Alternatively, the phase change associated with the onset of boiling maybe detected by a temperature sensor, such as a thermistor orthermocouple, located on the electrosurgical device 5, such as adjacentto the electrode. Also alternatively, the phase change associated withthe onset of boiling may be detected by a change in the electricproperties of the fluid itself. For example, a change in the electricalresistance of the fluid may be detected by an ohm meter; a change in theamperage may be measured by an amp meter; as change in the voltage maybe detected by a volt meter; and a change in the power may be determinedby a power meter.

Yet another control strategy which may be employed for theelectrosurgical device 5 is to eliminate the heat conduction term ofequation (1) (i.e. ΔT/R). Since the amount of heat conducted away toadjacent tissue can be difficult to precisely predict, as it may vary,for example, by tissue type, it may be preferable, from a control pointof view, to assume the worst case situation of zero heat conduction, andprovide enough saline so that if necessary, all the RF power could beused to heat up and boil the saline, thus providing that the peak tissuetemperature will not go over 100° C. a significant amount. Thissituation is shown in the schematic graph of FIG. 3.

Stated another way, if the heat conducted to adjacent tissue 70 isoverestimated, the power P required to intersect the 100% boiling line80 will, in turn, be overestimated and the 100% boiling line 80 will betransgressed into the T>>100° C. region of FIG. 2, which is undesirableas established above. Thus, assuming the worse case situation of zeroheat conduction provides a “safety factor” to avoid transgressing the100% boiling line 80. Assuming heat conduction to adjacent tissue 70 tobe zero also provides the advantage of eliminating the only term fromequation (1) which is tissue dependent, i.e., depends on tissue type.Thus, provided ρ, c_(p), ΔT, and h_(v) are known as indicated above, theequation of the line for any line of constant % boiling is known. Thus,for example, the 98% boiling line, 80% boiling line, etc. can bedetermined in response to a corresponding input from the selectionswitch 12. In order to promote flexibility, it should be understood thatthe input from the selection switch preferably may comprise anypercentage of boiling. Preferably the percentage of boiling may beselected in single percent increments (i.e. 100%, 99%, 98%, etc.).

Upon determination of the line of the onset of boiling 76, the 100%boiling line 80 or any line of constant % boiling there between, it isgenerally desirable to control the flow rate Q so that it is always on aparticular line of constant % boiling for consistent tissue effect. Insuch a situation, the flow rate controller 11 will adjust the flow rateQ of the fluid 24 to reflect changes in power P provided by thegenerator 6, as discussed in greater detail below. For such a use theflow rate controller 11 may be set in a line of constant boiling mode,upon which the % boiling is then correspondingly selected.

As indicated above, it is desirable to control the saline flow rate Q sothat it is always on a line of constant % boiling for consistent tissueeffect. However, the preferred line of constant % boiling may vary basedon the type of electrosurgical device 5. For example, if with use of thedevice 5, shunting through saline is not an issue, then it can bepreferable to operate close to or directly on, but not over the line ofthe onset of boiling, such as 76 a in FIG. 3. This preferably keepstissue as hot as possible without causing desiccation. Alternatively, ifwith use of the device 5 shunting of electrical energy (e.g. from onejaw to an opposing jaw of certain copative bipolar devices) throughexcess saline is an issue, then it can be preferable to operate along aline of constant boiling, such as line 78 a in FIG. 3, the 50% line.This simple proportional control will have the flow rate determined byequation (4), where K is the proportionality constant:Q ₁ =K×P   (4)

In essence, when power P goes up, the flow rate Q will beproportionately increased. Conversely, when power P goes down, the flowrate Q will be proportionately decreased.

The proportionality constant K is primarily dependent on the fraction ofsaline that boils, as shown in equation (5), which is equation (3)solved for K after eliminating P using equation (4), and neglecting theconduction term (ΔT/R):

$\begin{matrix}{K = \frac{1}{\left\{ {{\rho\; c_{p}\Delta\; T} + {\rho\; h_{v}{Q_{b}/Q_{l}}}} \right\}}} & (5)\end{matrix}$

Thus, the present invention provides a method of controlling boiling offluid, such as a conductive fluid, at the tissue/electrode interface. Ina preferred embodiment, this provides a method of treating tissuewithout use of tissue sensors, such as temperature or impedance sensors.Preferably, the invention can control boiling of conductive fluid at thetissue/electrode interface and thereby control tissue temperaturewithout the use of feedback loops.

In describing the control strategy of the present invention describedthus far, focus has been drawn to a steady state condition. However, theheat required to warm the tissue to the peak temperature (T) may beincorporated into equation (1) as follows:P=ΔT/R+ρc _(ρ) Q ₁ ΔT+ρQ _(b) h _(v) +ρc _(ρ) VΔT/Δt   (6)

where ρc_(ρ)VΔT/Δt represents the heat required to warm the tissue tothe peak temperature (T) 68 and where:

-   -   ρ=Density of the saline fluid that gets hot but does not boil        (approximately 1.0 gm/cm³);    -   c_(ρ)=Specific heat of the saline (approximately 4.1        watt-sec/gm-° C.);    -   V=Volume of treated tissue    -   ΔT=(T−T_(∞)) the difference in temperature between the peak        tissue temperature (T) and the normal temperature (T_(∞)) of the        body tissue (° C.). Normal temperature of the body tissue is        generally 37° C.; and    -   Δt=(t−t_(∞)) the difference in time to achieve peak tissue        temperature (T) and the normal temperature (T_(∞)) of the body        tissue (° C.).

The inclusion of the heat required to warm the tissue to the peaktemperature (T) in the control strategy is graphically represented at 68in FIG. 4. With respect to 35 the control strategy, the effects of theheat required to warm the tissue to the peak temperature (T) 68 shouldbe taken into account before flow rate Q adjustment being undertaken todetect the location of the line of onset of boiling 76. In other words,the flow rate Q should not be decreased in response to a lack of boilingbefore at least a quasi-steady state has been achieved as the locationof the line of onset of boiling 76 will continue to move during thetransitory period. Otherwise, if the flow rate Q is decreased during thetransitory period, it may be possible to decrease the flow Q to a pointpast the line of onset of boiling 76 and continue past the 100% boilingline 80 which is undesirable. In other words, as temperature (T) isapproached the heat 68 diminishes towards zero such that the lines ofconstant boiling shift to the left towards the Y-axis.

FIG. 5 is an exemplary graph of flow rate Q versus % boiling for asituation where the RF power P is 75 watts. The percent boiling % isrepresented on the X-axis, and the saline flow rate Q (cc/min) isrepresented on the Y-axis. According to this example, at 100% boilingthe most desirable predetermined saline flow rate Q is 2 cc/min. Alsoaccording to this example, flow rate Q versus % boiling at the remainingpoints of the graft illustrates a non-linear relationship as follows:

TABLE 1 % Boiling and Flow Rate Q (cc/min) at RF Power P of 75 watts  0%17.4  10% 9.8  20% 6.8  30% 5.2  40% 4.3  50% 3.6  60% 3.1  70% 2.7  80%2.4  90% 2.2 100% 2.0

Typical RF generators used in the field have a power selector switch to300 watts of power, and on occasion some have been found to beselectable up to 400 watts of power. In conformance with the abovemethodology, at 0% boiling with a corresponding power of 300 watts, thecalculated flow rate Q is 69.7 cc/min and with a corresponding power of400 watts the calculated flow rate Q is 92.9 cc/min. Thus, when usedwith typical RF generators in the field, a fluid flow rate Q of about100 cc/min or less with the present invention is expected to suffice forthe vast majority of applications.

As discussed herein, RF energy delivery to tissue can be unpredictableand vary with time, even though the generator has been “set” to a fixedwattage. The schematic graph of FIG. 6 shows the general trends of theoutput curve of a typical general-purpose generator, with the outputpower changing as load (tissue plus cables) impedance Z changes. Loadimpedance Z (in ohms) is represented on the X-axis, and generator outputpower P (in watts) is represented on the Y-axis. In the illustratedembodiment, the electrosurgical power (RF) is set to 75 watts in abipolar mode. As shown in the figure, the power will remain constant asit was set as long as the impedance Z stays between two cut-offs, lowand high, of impedance, that is, for example, between 50 ohms and 300ohms in the illustrated embodiment. Below load impedance Z of 50 ohms,the power P will decrease, as shown by the low impedance ramp 28 a.Above load impedance Z of 300 ohms, the power P will decrease, as shownby the high impedance ramp 28 b. Of particular interest tosaline-enhanced electrosurgery is the low impedance cut-off (lowimpedance ramp 28 a), where power starts to ramp down as impedance Zdrops further. This change in output is invisible to the user of thegenerator and not evident when the generator is in use, such as in anoperating room.

FIG. 7 shows the general trend of how tissue impedance generally changeswith time for saline-enhanced electrosurgery. As tissue heats up, thetemperature coefficient of the tissue and saline in the cells is suchthat the tissue impedance decreases until a steady-state temperature isreached upon which time the impedance remains constant. Thus, as tissueheats up, the load impedance Z decreases, potentially approaching theimpedance Z cut-off of 50 ohms. If tissue is sufficiently heated, suchthat the low impedance cut-off is passed, the power P decreases alongthe lines of the low impedance ramp 28 a of FIG. 6.

Combining the effects shown in FIG. 6 and FIG. 7, it becomes clear thatwhen using a general-purpose generator set to a “fixed” power, theactual power delivered can change dramatically over time as tissue heatsup and impedance drops. Looking at FIG. 6, if the impedance Z drops from100 to 75 ohms over time, the power output would not change because thecurve is “flat” in that region of impedances. If, however, the impedanceZ drops from 75 to 30 ohms one would transgress the low impedancecut-off and “turn the corner” onto the low impedance ramp 28 a portionof the curve and the power output would decrease dramatically.

According to one exemplary embodiment of the invention, the controldevice, such as flow rate controller 11, receives a signal indicatingthe drop in actual power delivered to the tissue and adjusts the flowrate Q of saline to maintain the tissue/electrode interface at a desiredtemperature. In a preferred embodiment, the drop in actual power Pdelivered is sensed by the power measurement device 8 (shown in FIG. 1),and the flow rate Q of saline is decreased by the flow rate controller11 (also shown in FIG. 1). Preferably, this reduction in saline flowrate Q allows the tissue temperature to stay as hot as possible withoutdesiccation. If the control device was not in operation and the flowrate Q allowed to remain higher, the tissue would be over-cooled at thelower power input. This would result in decreasing the temperature ofthe tissue at the treatment site.

The flow rate controller 11 of FIG. 1 can be a simple “hard-wired”analog or digital device that requires no programming by the user or themanufacturer. The flow rate controller 11 can alternatively include aprocessor, with or without a storage medium, in which the determinationprocedure is performed by software, hardware, or a combination thereof.In another embodiment, the flow rate controller 11 can includesemi-programmable hardware configured, for example, using a hardwaredescriptive language, such as Verilog. In another embodiment, the flowrate controller 11 of FIG. 1 is a computer, microprocessor-drivencontroller with software embedded. In yet another embodiment, the flowrate controller 11 can include additional features, such as a delaymechanism, such as a timer, to automatically keep the saline flow on forseveral seconds after the RF is turned off to provide a post-coagulationcooling of the tissue or “quench,” which can increase the strength ofthe tissue seal. Also, in another embodiment, the flow rate controller11 can include a delay mechanism, such as a timer, to automatically turnon the saline flow several seconds before the RF is turned on to inhibitthe possibility of undesirable effects as sticking, desiccation, smokeproduction and char formation. Also in another embodiment, the flow ratecontroller 11 can include a low level flow standby mechanism, such as avalve, which continues the saline flow at a standby flow level (whichprevents the flow rate from going to zero when the RF power is turnedoff) below the surgical flow level ordinarily encountered during use ofthe electrosurgical device 5.

An exemplary electrosurgical device of the present invention which maybe used in conjunction with the system of the present invention is shownat reference character 5 a in FIG. 9, and more particularly in FIGS.9-13. While various electrosurgical devices of the present invention aredescribed with reference to use with the remainder of the system of theinvention, it should be understood that the description of thecombination is for purposes of illustrating the remainder of the systemof the invention only. Consequently, it should be understood that theelectrosurgical devices of the present invention can be used alone, orin conjuction with the remainder of the system of the invention, or thata wide variety of electrosurgical devices can be used in connection withthe remainder of the system of the invention. The electrosurgicaldevices disclosed herein are preferably further configured for both openand laparoscopic surgery. For laparoscopic surgery, the devices arepreferably configured to fit through either a 5 mm or 12 mm trocarcannula.

As shown in FIG. 8, electrosurgical device 5 a may be used inconjunction with a cannula as illustrated at reference character 19,during laparoscopic surgery such as, for example, a laparoscopiccholecystectomy. Cannula 19 comprises a proximal portion 19 a separatedfrom a distal portion 19 b by an elongated rigid shaft portion 19 c.Proximal portion 19 a of cannula 19 preferably comprises a head portion19 d connected to rigid shaft portion 19 c, preferably by threadedengagement. Most importantly, cannula 19 has a working channel 19 ewhich extends through head portion 19 d and shaft portion 19 c fromproximal portion 19 a to distal portion 19 b of cannula 19. In oneparticular embodiment, during insertion into cannula 19, electrosurgicaldevice 5 a is configured to enter the proximal end of working channel 19e, move along the channel 19 e distally, and then be extended from thedistal end of the working channel 19 e. In the same embodiment, duringretraction from cannula 19, electrosurgical device 5 a is configured toenter the distal end of working channel 19 e, move along the channel 19e proximally, and then be removed from the proximal end of workingchannel 19 e.

Referring back to FIG. 9, as shown electrosurgical device 5 a comprisesa monopolar electrosurgical device. As shown in FIG. 9, electrosurgicaldevice 5 a preferably includes a rigid, self-supporting, hollow shaft17, a proximal handle comprising mating handle portions 20 a, 20 b and atip portion as shown by circle 45. Handle 20 a, 20 b is preferably madeof a sterilizable, rigid, non-conductive material, such as a polymer(e.g. polycarbonate). As shown in FIGS. 10 and 11, tip portion 45includes a contact element preferably comprising an electrode 25 which,as shown, comprises a solid ball having a smooth, uninterrupted surface.Also as shown in FIGS. 10 and 11, tip portion 45 also comprises a sleeve82 having a uniform diameter along its longitudinal length, a spring 88and a distal portion of shaft 17. As shown in FIG. 10, the longitudinalaxis 31 of the tip portion 45 may be configured at an angle A relativeto the longitudinal axis 29 of the proximal remainder of shaft 17.Preferably the longitudinal axis 31 of the tip portion 45 is configuredat an angle A of about 5 degrees to 90 degrees relative to thelongitudinal axis 29 of the proximal remainder of shaft 17. Morepreferably, the longitudinal axis 31 of tip portion 45 is configured atan angle A of about 8 degrees to 45 degrees relative to the longitudinalaxis of 29 of the proximal remainder of shaft 17.

As shown in FIGS. 10 and 11, for electrosurgical device 5 a, electrode25 generally has a spherical shape with a corresponding sphericalsurface, a portion 42 of which is exposed to tissue 32 (less than 180degrees and more specifically about 100-120 degrees) at the distal endof device 5 a. When electrode 25 is in the form of a sphere, the spheremay have any suitable diameter. However, the sphere preferably has adiameter in the range between and including about 1 mm to about 7 mm.Although, it has been found that when a sphere is larger than about 4 mmand less than about 2 mm tissue treatment can be adversely effected(particularly tissue treatment time) due to an electrode surface that isrespectively either to large or to small. Thus, more preferably thesphere has a diameter in the range between and including about 2.5 mm toabout 3.5 mm. Even more preferably, the sphere has a diameter of about 3mm.

It is understood that shapes other than a sphere can be used for thecontact element. Examples of such shapes include oblong or elongatedshapes. However, as shown in FIGS. 10 and 11, preferably a distal endsurface of electrosurgical device 5 a always provides a blunt, roundedsurface which is non-pointed and non-sharp as shown by electrode 25.

As shown in FIGS. 10 and 11, electrode 25, is preferably located in acavity 81 of a cylindrical sleeve 82 providing a receptacle forelectrode 25. Among other things, sleeve 82 guides movement of theelectrode 25. Among other things, sleeve 82 also functions as a housingfor retaining the electrode 25.

Also as shown in FIG. 11, a portion 44 of the electrode 25, is retainedwithin the cavity 81 while another portion 43 extends distally throughthe fluid outlet opening provided by circular fluid exit hole 26. Alsoas shown, sleeve 82 is connected, preferably via welding with silversolder, to the distal end 53 of shaft 17. For device 5 a, electrode 25,sleeve 82 and shaft 17 preferably comprise, and more preferably at leastessentially consists of, an electrically conductive metal, which is alsopreferably non-corrosive, and more particularly stainless steel. Othermetals include copper, titanium, gold, silver and platinum. Furthermore,shaft 17 preferably comprises thick walled stainless steel hypo-tubing.

As for cavity 81, the internal diameter of cavity 81 surrounding theelectrode 25, is preferably slightly larger than the diameter of thesphere, typically by about 0.25 mm. This permits the sphere to freelyrotate within the cavity 81. Consequently, cavity 81 of sleeve 82 alsopreferably has a diameter in the range of about 1 mm to about 7 mm.

As best shown in FIGS. 11 and 12, in order to retain the electrode 25,within the cavity 81 of sleeve 82, preferably the fluid exit hole 26,which ultimately provides a fluid outlet opening, of cavity 81 at itsdistal end 83 comprises a distal pinched region 86 which is reduced to asize smaller than the diameter of the electrode 25, to inhibit escape ofthe electrode 25 from the sleeve 82. More preferably, the fluid exithole 26 comprises a diameter smaller than the diameter of the electrode25.

As best shown in FIG. 12, the fluid exit hole 26 preferably has adiameter smaller than the diameter of the electrode 25, which can beaccomplished by at least one crimp 84 located at the distal end 83 ofthe sleeve 82 which is directed towards the interior of the sleeve 82and distal to the portion 44 of the electrode 25 confined in cavity 81.Where one crimp 84 is employed, the crimp 84 may comprise a singlecontinuous circular rim pattern. In this manner, the contact elementportion extending distally through the fluid outlet opening (i.e.electrode portion 43) provided by fluid exit hole 26 has a complementaryshape to the fluid outlet opening provided by fluid exit hole 26, hereboth circular.

However, as shown in FIG. 12, the crimp 84 may also comprise adiscontinuous circular rim pattern where the crimp 84 is interrupted byat least one rectangular hole slot 85 formed at the distal end 83 of thesleeve 82. Thus, the fluid outlet opening located at the distal end ofthe device 5 a may comprise a first portion (e.g. the circular fluidexit hole portion 26) and a second portion (e.g. the slot fluid exithole portion 85. As shown in FIG. 12, preferably, crimp 84 comprises atleast four crimp sections forming a circular rim pattern separated byfour discrete slots 85 radially located there between at 90 degreesrelative to one another and equally positioned around the fluid outletopening first portion. Slots 85 are preferably used to provide a fluidoutlet opening or exit adjacent the electrode 25, when the electrode isfully seated (as discussed below) and/or when the electrode 25 is not inuse (i.e. not electrically charged) to keep surface portion 42 of theelectrode surface of electrode 25 wet. Preferably, slots 85 have a widthin the range between and including about 0.1 mm to 1 mm, and morepreferably have a width in the range between and including about 0.2 mmto 0.3 mm. As for length, slots 85 preferably have a length in the rangebetween and including about 0.1 mm to 1 mm, and more preferably have alength in the range between and including about 0.4 mm to 0.6 mm.

As shown in FIG. 12, the contact element portion extending distallythrough the fluid outlet opening (i.e. electrode portion 43) extendsdistally through the fluid outlet opening first portion (e.g. thecircular fluid exit hole portion 26) and does not extend distallythrough the fluid outlet opening second portion (e.g. the slot fluidexit hole portion 85). In this manner an edge 91 of the slot 85 remainsexposed to tissue 32 to provide a tissue separating edge as discussedbelow.

It should be understood that the particular geometry of fluid outletopening provided by the fluid exit hole located at the distal end of thedevice 5 a to the electrode, is not critical to the invention, and allthat is required is the presence of a fluid exit hole which providesfluid 24 as required. For example, the fluid exit hole 26 may comprisean oval shape while electrode 25, comprises a different shape, such as around shape.

As shown in FIG. 12, in addition to slot 85 providing a fluid exit, atleast one edge 91 of slot 85 may provide a tissue separating edgeadjacent a blunt surface (e.g. surface portion 42 of the electrode 25)which may be used for blunt dissection when the electrosurgical device 5a is manipulated, particularly by rotating (e.g. twirling), abrading orimpacting. When edge 91 is used in such regard, it is preferred that theedge comprise a sharp edge with a sharp angle which has not been roundedby, for example, a fillet.

Turning to the proximal end of the tip (comprising the electrode 25,spring 88 and sleeve 82) of the device 5 a and electrode 25, as shown inFIG. 11, preferably the portion of the sleeve 82 proximal to theelectrode 25, also has a proximal pinched region 87 which retains theelectrode 25 in the cavity 81 of the sleeve 82 and inhibits escape ofthe electrode 25 from the cavity 81 of the sleeve 82, such as a diametersmaller than the diameter of the electrode 25.

While distal pinched region 86 and proximal pinched region 87 may beused solely to support the electrode 25, in its position of use, theelectrode may be further supported by a compression spring 88 as shownin FIG. 11. The use of spring 88 is preferred to provide a variablelength support within the working length of the spring 88 for overcomingmanufacturing tolerances (e.g. length) between the fixed supports (i.e.pinched regions 86 and 87) of the sleeve 82. As for maintaining properlocation of the spring 88, sleeve 82 also comprises a lumen 89 as shownin FIG. 11 (i.e. the cavity of an elongated hollow structure, such as atube or tube like structure; typically cylindrical) which, in additionto providing a direct passage for fluid, provides a guide tube forspring 88. Furthermore, the surface portion 60 of electrode 25, whichcontacts the spring 88 may comprise a flat surface rather than acurvilinear surface to better seat the spring against the electrode 25.

In addition to the above, spring 88 provides a multitude of functionsand advantages. For example, the configuration of the distal pinchedregion 86, proximal pinched region 87 and spring 88 offers the abilityto move the electrode 25, distally and proximally within sleeve 82. Asshown in FIG. 11, spring 88 is located proximal to the electrode 25between a first load bearing surface comprising the electrode surface 60and a second load bearing surface comprising the distal end 53 of shaft17. In this manner, spring 88 can be configured to provide adecompression force to seat the electrode 25 against the distal pinchedregion 86, in this case the perimeter edge 92 of crimp 84, prior to useof the electrosurgical device 5 a.

Conversely, upon application of the electrode 25, of the device 5 aagainst the surface 22 of tissue 32 with sufficient force to overcomethe compression force of the spring 88, spring 88 compresses and theelectrode 25 retracts proximally away from distal pinched region 86, inthis case perimeter edge 92 of crimp 84, changing the position thereof.In the above manner, the contact element comprising electrode 25 isretractable into the cavity 81 of the housing provided by sleeve 82 uponthe application of a proximally directed force against surface 42 of theportion 43 of the electrode 25 extending distally beyond the distalopening 26 located at the distal end 83 of the housing and spring 88functions as a retraction biasing member.

By making the electrode 25, positionable in the above manner via spring88, in various embodiments the electrosurgical device 5 a can beprovided with a damper mechanism which dampens the force of theelectrode 25 on tissue 32 being treated.

Furthermore, in various embodiments the electrosurgical device 5 a, anelectrode 25 which can be positioned as outlined above can comprise afluid flow rate adjustment mechanism which incrementally increases thearea of the fluid exit hole 26 and the corresponding fluid flow rate inresponse to the incremental proximal retraction of the electrode 25. Insuch an instance the electrode 25 functions as a valve in regulatingflow of the fluid 24 through fluid exit hole 26.

In various embodiments, spring 88 may be used in conjunction with thedistal pinched region 86 (e.g. crimp 84 comprising a single continuouscircular pattern) to provide a fluid seal between the electrode 25 andthe distal pinched region 86 which stops fluid flow from theelectrosurgical device 5 a. In this manner, the electrosurgical 5 adevice may be used to provide both a wet electrode and dry electrode(i.e. when the fluid flow is on and off, respectively) with the energyand fluid provided sequentially in addition to simultaneously. Theincorporation of a dry electrode function into the device of the currentinvention may be desirable to provide a mechanism for electrosurgicalcutting.

Furthermore, in various embodiments of electrosurgical device 5 a, anelectrode 25 which can be positioned as outlined above can comprise adeclogging mechanism which retracts to provide access for uncloggingfluid exit holes, such as fluid exit holes 26 and 85, which may becomeflow restricted as a result of loose debris (e.g. tissue, blood)becoming lodged therein. For example, when a biasing force, such as froma handheld cleaning device (e.g. brush) or from pushing the distal tipagainst a hard surface such as a retractor, is applied to surface 42 ofelectrode 25 which overcomes the compression force of the spring 88causing the spring 88 to compress and the electrode 25 to retract, thetip of the handheld cleaning device may by extended into the fluid exithole 26 for cleaning the fluid exit hole 26, perimeter edge 92, slot 85and edge 91. Stated another way, an electrode 25, which can bepositioned as outlined, provides a method for declogging a fluid exithole by increasing the cross-sectional area of the fluid exit hole toprovide access thereto.

Also, in various embodiments of the electrosurgical device 5 a, thespring 88 comprises an electrical conductor, particularly when theelectrode 25, is retracted to a non-contact position (i.e. not incontact) with the sleeve 82.

In other embodiments, proximal pinched region 87 may comprise one ormore crimps similar to distal pinched region 86, such that electrode 25is retained in sleeve 82 both distally and proximally by crimps. Also,in other embodiments, sleeve 82 may be disposed within shaft 17 ratherthan being connected to the distal end 53 of shaft 17. Also, in stillother embodiments, sleeve 82 may be formed unitarily (i.e. as a singlepiece or unit) with shaft 17 as a unitary piece.

As best shown in FIGS. 10 and 11, the electrode 25 is retained in thesleeve 82 such that a portion 43 of the electrode 25 extends distallybeyond distal end 83 of the sleeve 82. As shown, preferably the surface42 of this exposed portion 43 of the electrode 25 is blunt and does notcomprise any sharp corners. Also, the portion 43 of the electrode 25which extends distally beyond the distal end 83 of the sleeve 82 iscontrolled by the shape of the fluid exit hole 26 in sleeve 82 inrelation to the shape of the electrode 25. In other words, the portion43 of the electrode 25 which extends distally beyond the distal end 83of the sleeve 82 is controlled by the contact of the electrode surfacewith the edge 92.

As shown in FIGS. 10 and 11, in locations where shaft 17 and sleeve 82are electrically conductive (for device 5 a, preferably shaft 17 andsleeve 82 are completely electrically conductive and do not comprisenon-conductive portions), preferably an electrical insulator 90 (i.e.comprising non-conductive or insulating material) preferably surroundsshaft 17 and sleeve 82 along substantially its entire exposed length(e.g. the portion outside the confines of the handle 20), terminating ashort distance (e.g. at the proximal onset of the crimp 84 or less thanabout 3 mm) from distal end 83 of the sleeve 82. Insulator 90 preferablycomprises a shrink wrap polymer tubing.

As with the other electrosurgical devices described within, a inputfluid line 4 b and a power source, preferably comprising generator 6preferably providing RF power via cable 9, are preferably fluidly andelectrically coupled, respectively, to the tip portion 45 of theelectrosurgical device 5 a.

As indicated above, device 5 a comprises a monopolar device. In otherwords, a first electrode, often referred to as the active electrode,comprises an electrode of the electrosurgical device 5 a (e.g. electrode25) while a second electrode, often referred to as the indifferent orreturn electrode, comprises a ground pad dispersive electrode located onthe patient, typically on the back or other suitable anatomicallocation. Preferably, both electrodes are electrically coupled to thegenerator 6 to form an electrical circuit. Preferably the activeelectrode is coupled to the generator 6 via a wire conductor frominsulated wire cable 9 to the outer surface 18 of the shaft 17 withinthe confines of the handle 20 a, 20 b, typically through a switch 15 a.

In other embodiments, the shaft 17 may be made of an electricalnon-conducting material except for a portion at its distal end 53 thatcomes in contact with sleeve 82. This portion of shaft 17 that contactsthe sleeve 82 should be electrically conducting. In this embodiment, thewire conductor from insulated wire cable 9 extends to this electricallyconducting portion of shaft 17. In still other embodiments, the shaft 17may completely comprise a non-conducting material as where the wireconductor from insulated wire cable 9 extends directly to the sleeve 82.

With respect to the fluid coupling, fluid 24 from the fluid source 1 foruse with electrosurgical device 5 a preferably is communicated fromfluid source 1 through a flexible, polyvinylchloride (PVC) outlet fluidline 4 a to a flexible, polyvinylchloride (PVC) inlet fluid line 4 bconnected to the electrosurgical device 5 a. The outlet fluid line 4 aand the inlet fluid line 4 b are preferably connected via a male andfemale mechanical fastener configuration, preferably comprising aLuer-Lok® connection from Becton, Dickinson and Company. The lumen ofthe inlet line is then preferably interference fit over the outsidediameter of the shaft 17 to provide a press fit seal there between.Additionally an adhesive may be disposed there between to strengthen theseal. Fluid 24 is then communicated down the lumen 23 of the shaft 17through the lumen 89 and cavity 81 of the sleeve 82 where it is expelledfrom around and on the exposed surface 42 of the electrode 25. Thisprovides a wet electrode for performing electrosurgery.

As shown in FIG. 13, during use of electrosurgical device 5 a, typicallya fluid coupling 30 preferably comprising a discrete, localized web andmore preferably comprising a triangular shaped web or bead portionproviding a film of fluid 24 is provided between the surface 22 of thetissue 32 and electrode 25. When the user of electrosurgical device 5 aplaces the electrode 25 at a tissue treatment site and moves theelectrode 25 across the surface 22 of the tissue 32, fluid 24 isexpelled around and on the surface 42 of the electrode 25 at the distalend 83 of the sleeve 82 and onto the surface 22 of the tissue 32 viacoupling 30. The fluid 24, in addition to providing an electricalcoupling between the electrosurgical device 5 a and the tissue 32,lubricates the surface 22 of the tissue 32 and facilitates the movementof electrode 25 across the surface 22 of the tissue 32. During movementof the electrode 25, the electrode 25 typically slides across thesurface 22 of the tissue 32, but also may rotate as the electrode 25moves across the surface 22 of the tissue 32. Typically the user of theelectrosurgical device 5 a slides the electrode across the surface 22 ofthe tissue 32 back and forth with a painting motion while using thefluid 24 as, among other things, a lubricating coating. Preferably thethickness of the fluid 24 between the distal end surface of theelectrode 25 and the surface 22 of the tissue 32 at the outer edge ofthe coupling 30 is in the range between and including about 0.05 mm to1.5 mm. More preferably, the fluid 24 between the distal end surface ofthe electrode 25 and the surface 22 of the tissue 32 at the outer edgeof the coupling 30 is in the range between and including about 0.1 mm to0.3 mm. Also preferably, in certain embodiments, the distal end tip ofthe electrode 25 contacts the surface 22 of tissue 32 without any fluid24 in between.

Another exemplary electrosurgical device of the present invention whichmay be used in conjunction with the system of the present invention isshown at reference character 5 b in FIGS. 14-16. In this embodiment,electrical insulator 90 preferably terminates proximally to the sleeve82 where sleeve 82 is connected to the distal end 53 of shaft 17. Incertain embodiments where the sleeve 82 is formed unitary with the shaft17, the electrical insulator 90 preferably terminates proximally toproximal pinched region 87. In this manner, in addition to the sphericalsurface portion 42 of the electrode 25 and the narrowing surface portion41, here conical, of the sleeve 82 being used for treating tissue 32when exposed thereto, a cylindrical surface 40 of a cylindrical portion39 of the sleeve 82 and a broadening surface portion 47 of broadeningportion 54, here both conical, of the sleeve 82 also function aselectrode surfaces for treating tissue. Thus, the electrode exposed totissue 32 now comprises a cylindrical surface portion 40 and abroadening surface portion 47 in addition to the spherical surfaceportion 42 and the narrowing surface portion 41, with the cylindricalsurface portion 40 substantially increasing the surface area of theelectrode. As a result, the electrode 25 now also comprises surfaceswhich are parallel and perpendicular to the longitudinal axis 31 of thetip portion 45, and more particularly sleeve 82, of the electrosurgicaldevice 5 b. In the above manner, front end use (e.g. surfaces 41 and42), sideways use (e.g. surface 40 and 47) or oblique use (e.g. surfaces40, 41 and 42) of the electrosurgical device 5 b is facilitated.

In the above manner, the tip portion 45 now comprises a first tissuetreating surface (e.g. distal end spherical surface 42) and a secondtissue treating surface (e.g. side surface 40). As discussed above,preferably the first tissue treating surface is configured for bluntdissection while the second tissue treating surface is configured forcoagulation. Additionally, tip portion 45 also comprises a third tissuetreating surface (e.g. surface 41) located between the first tissuetreating surface (e.g. surface 42) and a second tissue treating surface(e.g. surface 40). Furthermore, tip portion 45 also comprises a fourthtissue treating surface (e.g. surface 47) located proximal and adjacentto surface 40.

With device 5 a, when the electrode 25, is placed directly in contactwith surface 22 of tissue 32, it may be possible for the tissue 32 toocclude fluid flow from the fluid exit holes 26, 85 located at thedistal end of the device 5 a. Consequently, for device 5 b fluid exitholes 93, 94 may be located in the cylindrical side portion 39 of thesleeve 82, either proximal or adjacent to the electrode 25, and eitherin addition to or as an alternative to fluid exit holes 26, 85.

As shown in FIGS. 14 and 15, at least one fluid exit hole 93 ispreferably formed in the cylindrical longitudinal side surface 40 andthrough the wall of side portion 39 of the sleeve 82 adjacent toelectrode 25 when electrode 25 is fully seated. Furthermore, preferablyat least one fluid exit hole 94 is formed in the cylindrical sideportion 39 of the sleeve 82 proximal to electrode 25 when electrode 25is fully seated.

Preferably, holes 93, 94 each comprise more than one hole which areequally spaced radially in a circular pattern around the longitudinalaxis 31 of the tip portion 45, and more particularly sleeve 82. Morepreferably, holes 93, 94 each comprise four discrete holes equallyspaced 90 degrees around the cylindrical side portion 39 of the sleeve82. Preferably holes 93, 94 have a diameter in the range between andincluding about 0.1 mm to 1.0 mm, and more preferably have a length inthe range between and including about 0.2 mm to 0.6 mm. Electrode 25which can be positioned as outlined above can comprise not only a valvefor regulating fluid flow from the fluid exit holes, such as fluid exithole 26, but also comprise a valve which while opening one fluid flowexit simultaneously closes another fluid flow exit. For example, aselectrode 25 retracts proximally, fluid exit hole 26 is opened whilefluid exit hole 93 is closed. Stated another way, an electrode 25 whichcan be positioned as outlined above can provide a mechanism for alteringthe size and/or location of the fluid exit holes during use of theelectrosurgical device 5 b which may be necessary, for example, todirect fluid to a particular tissue location or balance fluid flow amongthe fluid exit outlets.

Thus, as shown in FIGS. 14 and 15, surfaces 40, 41 and 47 of the sleeve82, and surface 42 of electrode 25 are all active electrode surfaces andcan provide electrical energy to tissue 32. Portions of this combinedelectrode surface can be wet by fluid flow from holes 26, 94 or 93, aswell as from the hole slots 85 in the crimp 84 adjacent the electrode25.

The holes 94, 93 in the cylindrical sleeve 82 of the overall electrodesurface are intended to assure that fluid 24 is provided to the smooth,less rough, atraumatic sides of the electrode that are used to producetissue coagulation and hemostasis (e.g. surfaces 40 and 47) rather thanblunt dissection (e.g. surfaces 41 and 42). The most distal portion ofthe device may have a more rough, but also wetted, electrode surfacethat can blunt dissect as well as coagulate tissue.

The electrode configuration shown in FIGS. 14 and 15 is particularlyuseful to a surgeon performing a liver resection. Once the outer capsuleof the liver is scored with a dry bovie blade along the planned line ofresection the distal tip of tip portion 45 is painted back and forthalong the line, resulting in coagulation of the liver parenchyma. As thetissue is coagulated under and around the electrode surfaces 40, 41 and42, the electrode is used to blunt dissect into the coagulatedparenchyma, with the edge 91 of the slots 85 around the crimp 84providing roughness elements that aid in disrupting the tissue 32 andenabling the parting of the tissue 32.

As shown in FIG. 16, the device 5 b can be used deeply in a crevice 97of tissue 32 to blunt dissect the tissue 32 and coagulate it at the sametime. Blunt dissection is preferred over sharp dissection, such as witha blade or scissors, since blunt dissection is less likely to tear ordamage the larger blood vessels or other vessels. Once identified byblunt dissection, larger vessels can be safely clipped, tied with sutureor sealed with some other device. If the larger vessels are not thusfirst “skeletonized” without being damaged by blunt dissection, they maybleed profusely and require much more time to stop the bleeding. Thedevice can also be used to coagulate first without simultaneous bluntdissection, and then blunt dissect in a separate step.

This technique can also be used on other parenchymal organs such as thepancreas, the kidney, and the lung. In addition, it may also be usefulon muscle tissue and subcutaneous fat. Its use can also extend to benigntumors, cysts or other tissue masses found in the urological orgynecological areas. It would also enable the removal of highlyvascularized tumors such as hemangiomas.

In FIG. 16 the zone 99 identifies the part of the electrode that has theability to blunt dissect and coagulate, and the zone 98 identifies thepart that is intended primarily for coagulation and hemostasis. The line100 indicates the depth of the zone of tissue that is coagulated,typically from 3 mm to 5 mm deep.

For the devices disclosed herein, the presence of various fractions ofboiling can be visually estimated by the naked eye, or by detectingchanges in electrical impedance. FIG. 17 shows a plot of electricalimpedance Z versus time t. The impedance spikes 101 shown in FIG. 17occur at a frequency of about 1 cycle per second and with an amplitudethat is on the same order as the baseline impedance. This frequency isshown in FIG. 17 as the interval 102 between successive impedancespikes. Impedance is directly measurable by dividing the voltage by thecurrent as previously described. The use of electrical impedance todetect the onset of tissue dessication when impedance rises dramaticallyas a result of being heated to the point of smoking and charring, butnot to detect the presence of boiling, is described above. As shown inFIG. 17, the impedance Z may change from a level of about 100 ohms withno boiling, to a level of about 400 ohms or more with a large fractionof the conductive fluid boiling. The percentages of boiling shown areexemplary as are the levels of impedance.

Shown in FIG. 18 is the qualitative nature of the boiling as the %boiling increases, indicated by the small figures for each of fiveexemplary “regimes” of boiling. In each small figure a portion of thetip of the tip portion 45 of the device 5 a is shown in close proximityto tissue 32. As boiling begins in regime 104, there are few smallbubbles 37 of vapor in the conductive fluid 24, here saline, of coupling30. As the percentage of boiling increases at regime 106 there are alarger number of small bubbles 37. As the percentage boiling increasesfurther at regime 107, the bubbles 37 become much larger. At even higherpercentage boiling at regime 108 intermittent threads of saline form andare quickly boiled off. Finally, at the highest level of regime 109,drops 36 of saline are instantly boiled upon contacting the hot surface22 of the tissue 32 and arcing occurs from the metal to the tissue 32.

Returning to FIGS. 14 and 15, fluid outlet openings are provided bysubstantially linear through holes 93, 94 which provide conductive fluid24 to the treatment site. However, in an alternative embodiment, asshown in FIG. 19, fluid outlet openings in the sleeve 82 may be providedby holes in the form of tortuous and interconnected pathways 59, whichare formed in a material pervious to the passage of fluid 24,therethrough, such as a porous material. The discrete, linear throughholes 93, 94 may be either supplemented with or replaced by a pluralityof tortuous, interconnected pathways 59 formed in the porous materialwhich, among other things, provides porous surfaces 40, 41 and 47 tomore evenly distribute fluid flow and provide the conductive fluid 24 totissue 32 at the treatment site. According to the invention, all or aportion of the sleeve 82 may comprise a material pervious to the passageof fluid 24 therethrough as disclosed herein.

In certain embodiments, the contact element, here electrode 25 may alsocomprise a material pervious to the passage of fluid 24, therethrough,such as a porous material (e.g. metal, polymer or ceramic) to providethe tortuous pathways 59. In these embodiments, the porous structure ofthe electrode 25 allows fluid 24 to not only pass around electrode 25 onthe outer porous surface 42 to be expelled, but also allows fluid 24 topass through the electrode 25, to be expelled. According to theinvention, all or a portion of the electrodes or any particularelectrodes for treating tissue 32 may comprise a material pervious tothe passage of fluid 24 therethrough as disclosed herein.

Where the contact element and sleeve provide electrodes for treatingtissue and compromise a porous material, preferably the porous materialfurther comprises porous metal. Porous sintered metal is available inmany materials (such as, for example, 316L stainless steel, titanium,Ni-Chrome) and shapes (such as cylinders, discs, plugs) from companiessuch as Porvair, located in Henderson, N.C.

Porous metal components can be formed by a sintered metal powder processor by injection molding a two-part combination of metal and a materialthat can be burned off to form pores that connect (open cell) to eachother. With sintering, for example, typically solid particles ofmaterial are placed in a mold under heat and pressure such that theouter surface of the particles soften and bond to one another with thepores comprising the interstices between the particles. Alternatively,when porosity is formed by burning off material, it is not theinterstice between the particles which provides the porosity as withsintering, but rather a partial evisceration of the material generallyprovided by the removal of a component with a lower melt temperaturethan the burn off temperature.

While the electrode provided by contact element and/or sleeve preferablycomprises an electrically conductive material such as metal, anon-electrically conductive porous contact element and/or sleeve, suchas porous polymers and ceramics, can be used to replace an electricallyconductive contact element and/or sleeve. While the porous polymers andceramics are generally non-conductive, they may also be used to conductthe RF energy through the porous polymer and ceramic thickness andporous surface to the tissue to be treated by virtue of conductive fluid24 contained within the plurality of interconnected tortuous pathways59.

Preferably the tortuous passages in the porous materials have a poresize (cross-sectional dimension) in the range between and includingabout 2.5 micrometers (0.0025 mm) to 500 micrometers (0.5 mm) and morepreferably has pore size in the range between and including about 10micrometers (0.01 mm) to 120 micrometers (0.12 mm). Even morepreferably, the porous material has a pore size in the range between andincluding about 20 micrometers (0.02 mm) to 80 micrometers (0.08 mm).

In addition to possibly providing a more uniform distribution of fluid24, the porous materials also may provide other advantages. For example,when the electrode surfaces, such as surfaces 40, 41, 42 and 47, incontact with the surface 22 of tissue 32 are porous and dissipate fluid24, the tissue 32 is less apt to stick to the surfaces 40, 41, 42 and 47of the electrode as compared to the situation where the surfaces 40, 41,42 and 47 are not porous. In addition, by providing fluid 24 to surfaces40, 41, 42 and 47 through tortuous pathways 59, heated and/orelectrified fluid 24 can now be provided more uniformly to surfaces 40,41, 42 and 47, which may result in a wider tissue treatment region ascompared to when the surfaces are not porous.

Preferably the porous material provides for the wicking (i.e. drawing inof fluid by capillary action or capillarity) of the fluid 24 into thepores of the porous material. In order to promote wicking of the fluid24 into the pores of the porous material, preferably the porousmaterial, and in particular the surface of the tortuous pathways, ishydrophilic. The porous material may be hydrophilic with or without posttreating (e.g. plasma surface treatment such as hypercleaning, etchingor micro-roughening, plasma surface modification of the molecularstructure, surface chemical activation or crosslinking), or madehydrophilic by a coating provided thereto, such as a surfactant.

Though not preferable, it is not necessary that fluid coupling 30 offluid 24 be present in between the metal electrode surfaces (e.g. 40,41, 42) and tissue 32 at all locations of tissue treatment and there maybe points of direct tissue contact by the electrode surfaces without anyfluid coupling 30 therebetween. In such an instance, the convectivecooling of the metal electrode by flowing saline is often sufficient tokeep the metal electrode and tissue contacting the metal electrode at orbelow a temperature of 100° C. In other words, heat may be also firstdissipated from the tissue 32 to the electrodes by conduction, thendissipated from the electrodes to the fluid 24 by convection.

Preferably the relationship between the material for electrodesparticularly their surfaces (e.g. 40, 41, 42, 47), and fluid 24throughout the various embodiments should be such that the fluid 24 wetsthe surface of the electrodes to form a continuous thin film coatingthereon (for example, see FIG. 19A) and does not form isolated rivuletsor circular beads (e.g. with a contact angle, θ greater than 90 degrees)which freely run off the surface of the electrode. Contact angle, θ, isa quantitative measure of the wetting of a solid by a liquid. It isdefined geometrically as the angle formed by a liquid at the three phaseboundary where a liquid, gas and solid intersect. In terms of thethermodynamics of the materials involved, contact angle θ involves theinterfacial free energies between the three phases given by the equationγ_(LV) cos θ=γ_(SV)−γ_(SL) where γ_(LV), γ_(SV) and γ_(SL) refer to theinterfacial energies of the liquid/vapor, solid/vapor and solid/liquidinterfaces, respectively. If the contact angle θ is less than 90 degreesthe liquid is said to wet the solid. If the contact angle is greaterthan 90 degrees the liquid is non-wetting. A zero contact angle θrepresents complete wetting. Thus, preferably the contact angle is lessthan 90 degrees.

For clarification, while it is known that the contact angle θ may bedefined by the preceding equation, in reality contact angle θ isdetermined by a various models to an approximation. According topublication entitled “Surface Energy Calculations” (dated Sep. 13, 2001)from First Ten Angstroms (465 Dinwiddie Street, Portsmouth, Va. 23704),there are five models which are widely used to approximate contact angleθ and a number of others which have small followings. The fivepredominate models and their synonyms are: (1) Zisman critical wettingtension; (2) Girifalco, Good, Fowkes, Young combining rule; (3) Owens,Wendt geometric mean; (4) Wu harmonic mean; and (5) Lewis acid/basetheory. Also according to the First Ten Angstroms publication, forwell-known, well characterized surfaces, there can be a 25% differencein the answers provided for the contact angle θ by the models. Also forclarification, any one of the five predominate models above whichcalculates a contact angle θ within a particular range of contact anglesθ or the contact angle θ required of a particular embodiment of theinvention should be considered as fulfilling the requirements of theembodiment, even if the remaining four models calculate a contact angleθ which does not fulfill the requirements of the embodiment.

The effects of gravity and surface tension tend to wick the fluid 24,here saline, around the circumference of the cylindrical sleeve 82 topreferably cover the entire active electrode surface. More specifically,the effects of gravity and surface tension on fluid 24 which is locatedon the electrode surfaces may be modeled by the Bond number N_(BO). Bondnumber N_(BO) measures the relationship of gravitational forces tosurface tension forces and may be expressed as:N _(BO)=gravitational force/surface tension forceN _(BO) =ρL ²g/σwhere:

-   -   ρ=Density of the saline fluid (approximately 1.0 gm/cm³);    -   L=droplet diameter (cm)    -   g=Gravitational acceleration (980 cm/s²)    -   σ=Surface tension (approximately 72.8 dynes/cm @20° C.)

For a Bond number N_(BO)=1, the droplet diameter is equal to about 0.273cm or about 2.7 mm, which is in the same order of magnitude as thepreferred size of the electrode. For the purposes of the presentinvention, preferably Bond number N_(BO) for a droplet of fluid 24 on asurface of the electrode 25 is preferably less than 1.

Another tip portion of an exemplary electrosurgical device 5 c of thepresent invention which may be used in conjunction with the system ofthe present invention is shown at reference character 45 in FIGS. 20-24.As best shown in FIGS. 20 and 21, the separate sleeve 82 of embodiments5 a and 5 b has been eliminated from tip portion 45 of device 5 c.Consequently, the contact element, still preferably comprising anelectrode 25, is assembled directly with the shaft 17. Electrode 25 ispreferably assembled (e.g. mechanically connected via press fit,mechanical connector, threaded, welded, adhesively bonded) adjacent thedistal end 53 of shaft 17. In certain embodiments, the electrode 25preferably is detachably assembled to the shaft 17 such that it may beremoved from the shaft 17, preferably manually by human hand, so thatthe shaft 17 may be used with multiple different contactelements/electrodes, or the shaft 17 may be reuseable and used withdisposable contact elements/electrodes.

As shown in FIGS. 20-24, electrode 25 preferably comprises an enlargedhead portion comprising a spherical portion 43 and a correspondingspherical surface portion 42 located at the distal end of the device 5 cwhich provided a smooth, blunt contour outer surface. More specifically,as shown, the spherical portion 43 and spherical surface portion 42further provide a domed, hemisphere (i.e. less than a full sphere) andhemispherical surface portion comprising preferably about 180 degrees.

Also as shown in FIGS. 20-24, the enlarged head portion of electrode 25preferably also comprises a cylindrical portion 39 and a correspondingcylindrical surface portion 40 located proximal and adjacent to thespherical portion 43 and spherical surface portion 42, respectively.

Further continuing with FIGS. 20-24, electrode 25 preferably comprises aconnector portion, preferably comprising a shank 46, which connects theremainder of the electrode 25 to the shaft 17. Among other things, theconnector portion of the electrode 25 is preferably configured to form aconnection with a mating connector portion of the shaft 17. As shown,preferably the shank portion 46 is configured to extend into cavity 50of shaft 17 which comprises a cylindrical receptacle and provides themating connector portion for shank 46. More preferably, surface 48 ofthe shank portion 46 is configured to mate against and form aninterference fit with surface 52 of cavity 50 to provide the connection.

Continuing with FIGS. 20-24, shank portion 46 is preferably cylindricaland located proximal and adjacent to a neck portion 56. As shown, hereneck portion 56 also comprises a cylindrical portion 57 (having acorresponding cylindrical surface portion 58) located proximal andadjacent to a broadening portion 54 (having a corresponding broadeningsurface portion 47). Here broadening portion 54 and correspondingbroadening surface portion 47 are both spherical, and more specificallycomprise a domed, hemisphere and hemispherical surface portioncomprising preferably about 180 degrees, located proximal and adjacentto the cylindrical portion 39 and cylindrical surface portion 40.

As shown in FIGS. 20-24, the cylindrical portion 57 of neck portion 56preferably has a cross-sectional dimension, here diameter, greater thanthe cross-sectional dimension, here also diameter, of the shank 46. Inthis manner, in certain embodiments, the proximal end of the neckportion 56 may be located adjacent and in contact with the distal end 53of shaft 17.

Also as shown in FIGS. 20-24, electrode 25 comprises at least one recess64 which provides an elongated fluid flow channel for the distributionof fluid 24. The use of device 5 c, and in particular recesses 64, forthe distribution of fluid 24 is generally preferred to the fluid exitholes 93, 94 of device 5 b in particularly deep tissue crevices 97 wheretissue 32 can occlude fluid flow from the fluid exit holes located inthe cylindrical portion 39 of the electrode 25.

As shown, electrode 25 preferably comprises a plurality oflongitudinally directed recesses 64 and, more specifically, fourrecesses 64 equally spaced 90 degrees around the shank 46 and/or neckportion 56, both proximal of cylindrical portion 39. As best shown inFIG. 24, in certain embodiments, the recess 64 may comprise a first sidewall 64 a, a second opposing side wall 64 b, and a bottom wall 64 c.

In use, when tissue 32 overlies and occludes the fluid outlet opening 55of recess 64 for a portion of its longitudinal length, thus inhibitingfluid 24 from exiting therefrom, fluid 24 from recess 64 may still beexpelled from the electrosurgical device 5 c after flowinglongitudinally in the channel 64 to a remote location where the channel64 is unoccluded and uninhibited to fluid flow exiting therefrom.

However, in certain instances, it may be possible that the recess 64 maybe occluded by tissue 32 completely along its longitudinal length, thuscompletely inhibiting fluid flow from exiting through opening 55. Inorder to overcome this problem, at least a portion of the electrode 25may comprise a material pervious to the passage of fluid 24,therethrough, such as a porous material described above.

As shown in FIG. 25, in another embodiment of the electrosurgical deviceof the present invention, as shown at reference character 5 d in FIG.25, the walls 64 a, 64 b of recess 64, surface 48 of the shank portion46, and/or the surfaces of the neck portion 56 of electrode 25 may beporous and connected by a plurality of tortuous pathways 59 in theporous material. Consequently, rather than flowing out of recess 64 froma direct fluid outlet opening 55, which may be occluded by tissue 32,the fluid 24 may exit indirectly from recess 64 by first flowing throughtortuous pathways 59 of the electrode 25 from side walls 64 a, 64 b ofthe recess 64 and then exit the electrode 25 from surface 58, which maybe in unoccluded by tissue 32. Alternatively, if adjacent surface 58 ofthe electrode 25 is also occluded by tissue 32, the fluid 24 maycontinue to flow through tortuous pathways 59 of electrode 25 and exitelectrode 25 from a surface 64 a, 64 b of a recess 64 or surface such as40, 42, 47 or 58 which may be in unoccluded by tissue 32.

Where the electrode 25 comprises a porous material, recess 64 may beeither supplemented with or replaced by the plurality of tortuous,interconnected passages 59 formed in the porous material as shown inFIG. 25, with porous surfaces such as 40, 42, 47 or 58 to more evenlydistribute fluid flow and provide conductive fluid 24 to the tissuetreatment site. All or a portion of the electrodes can be porousaccording to the invention.

In other embodiments of the invention, recess 64 may comprisecross-sectional shapes other than rectangular shapes. For example, asshown in FIGS. 26-28 recess 64 comprises a semi-circular shape, aV-shape, or a U-shape respectively, or any combination thereof.

Returning to FIG. 21, in order to facilitate direct fluid communicationof recess 64 with lumen 23 of shaft 17, preferably recesses 64 of device5 c are initiated within the confines of shaft 17. In other words,within the cavity 50 of shaft 17 proximal to distal end 53. Preferablythe configuration of the recesses 64 as provided by geometry (e.g.width, depth) and/or the material and/or surface treatment of theelectrode 25 may be arranged such that surface tension will act toretain fluid collected in the recess 64 where the force of gravity isacting to remove the fluid from the recess 64. However, while it isdesirable that a certain predetermined amount of surface tension act toretain fluid collected in the recess 64 in the presence of gravity, thesurface tension must be balanced against the inhibition of fluid flowfrom the recess 64.

As indicated above, the use of device 5 c, and in particular recesses64, for the distribution of fluid 24 is generally preferred to the fluidexit holes 93, 94 of device 5 b in particularly deep tissue crevices 97where tissue 32 can occlude fluid flow from the fluid exit holes 93, 94located in the cylindrical portion 39 of the electrode 25. Also, sinceholes 93, 94 are not presented with a declogging mechanism, such asprovided for such as fluid exit holes 26 and 85, holes such as 93, 94that can be simply occluded by ordinary tissue/electrode contact willsooner or later become irreversibly clogged.

As shown in FIG. 21, with device 5 c fluid outlet openings 73 areprovided by the structure of the electrode 25 (i.e. recesses 64) at thedistal end 53 of the shaft 17 which are protected and sheltered fromcontact and occlusion from surface 22 of tissue 32. Fluid outletopenings 73 of device 5 c are protected from occlusion from surface 22of tissue 32 as the structure of device 5 c defining the openings 73 isat least partially configured for non-contact with surface 22 of tissue32. More specifically, here the structure of the device defining theopenings 73 is completely configured for non-contact with surface 22 oftissue 32. Stated another way, the openings 73 are provided on thedevice 5 c at a location removed from the tissue surface 22. Also, asshown, openings 73 are particularly sheltered from occlusion fromsurface by 22 of tissue 32 by a portion of the shaft 17. Also as shown,when openings 73 are formed substantially perpendicular to the surface22 of tissue 32 and thus turned away from direct contact with surface 22of tissue 32.

Another tip portion of an exemplary electrosurgical device 5 e of thepresent invention which may be used in conjunction with the system ofthe present invention is shown at reference character 45 in FIGS. 29-32.As best shown in FIGS. 31 and 32, the broadening portion 54 has beeneliminated and the cylindrical portion 39 has an equal cross-sectionaldimension, here diameter, with the neck portion 56. Conversely, fordevice 5 c, the cylindrical portion 39 has a cross-sectional dimension,there also diameter, greater than the cross-sectional dimension, therealso diameter, of the neck portion 56.

Also as shown in FIGS. 31 and 32, the cylindrical portion 39 furthercomprises a rectilinear (straight) cylindrical portion 39 a having arectilinear cylindrical surface portion 40 a and a curvilinearcylindrical portion 39 b having a curvilinear cylindrical surfaceportion 40 b. As shown, device 5 e comprises the shape of a hockeystick. The cylindrical portion 39 for device 5 c may be similarlyarranged.

Another tip portion of an exemplary electrosurgical device 5 f of thepresent invention which may be used in conjunction with the system ofthe present invention is shown at reference character 45 in FIGS. 33-36.As best shown in FIGS. 35 and 36, the cylindrical portion 39 has across-sectional dimension, here diameter, less than the cross-sectionaldimension, here also diameter, of the neck portion 56. As shown the neckportion 56 is located proximal and adjacent to a narrowing portion 49with a corresponding narrowing surface portion 51, here both conical.

Also as shown in FIG. 34, the cylindrical portion 39 further comprises arectilinear cylindrical portion 39 a having a rectilinear cylindricalsurface portion 40 a and a curvilinear cylindrical portion 39 b having acurvilinear cylindrical surface portion 40 b. Furthermore, as shown, thecylindrical portion 39, and more specifically at least one of therectilinear cylindrical portion 39 a and the curvilinear cylindricalportion 39 b, comprises a portion of a hook. Preferably, as shown boththe rectilinear cylindrical portion 39 a and the curvilinear cylindricalportion 39 b comprise portions of a hook. As shown in FIGS. 35 and 36,the hook further comprises an L-hook.

Another tip portion of an exemplary electrosurgical device 5 g of thepresent invention which may be used in conjunction with the system ofthe present invention is shown at reference character 45 in FIGS. 37-38.As shown, for device 5 g the cylindrical portion 39, and morespecifically both the rectilinear cylindrical portion 39 a and thecurvilinear cylindrical portion 39 b comprise portions of a hook. Alsoas shown in FIGS. 37 and 38, the hook further comprises an J-hook.

Another tip portion of an exemplary electrosurgical device 5 h of thepresent invention which may be used in conjunction with the system ofthe present invention is shown at reference character 45 in FIGS. 39-42.As shown in FIGS. 39 and 40, electrode 25 preferably comprises a fingerportion 65 (preferably comprising cylindrical portion 39 and cylindricalsurface portion 40) having a distal end (preferably comprising aspherical portion 43 and spherical surface portion 42) which, amongother things, is configured for blunt dissection or electrosurgicaldissection of tissue 32. Electrosurgical dissection occurs when tensionor force is applied to tissue while also applying RF energy. The RFenergy heats the tissue, thereby weakening it, and the tissue yields orbreaks where desired. Surgeons may refer to this type of dissection witha hook-type electrode as “hook and cook”. Furthermore, finger portion 65is also preferably configured to function as a hook, particularly theanterior (i.e. front) surface portion 66 of finger portion 65 which isconfigured, among other things, to engage and restrain tissue 32.

As shown, finger portion 65 is rectilinear and forms an L-hook with anangle of about 90 degrees relative to the longitudinal axis 31 of thetip portion 45, particularly shank 45. However, finger portion may beformed at angles other than 90 degrees. For example. finger portion 65may be formed at any angle in the range between and including about 60degrees relative to the tip portion 45 to about 180 degrees relative tothe tip portion 45, or any other range of angles or particular angleinclusive therein (e.g. 75°, 105°, 120°, 135°, 180°, 90°-135°,90°-180°).

Among other things, electrode 25 preferably comprises a knuckle portion61 comprising a rounded protuberance having a raised prominence on theposterior (back) surface portion 62 of the electrode 25. Also as shown,knuckle portion 61 also comprises a rounded protuberance having a raisedprominence on the lateral surface portion 75 of the electrode 25. Amongother things, posterior knuckle surface portion 62 and lateral knucklesurface portion 75 formed by knuckle portion 61 are configured forcoagulation and stasis (e.g. hemostasis, aerostasis) of tissue 32.

Key to device 5 g is the cross-sectional dimension of the knuckle Z tothe cross-section dimension of the finger F. When comparing thefunctions of blunt or electrosurgical dissection andcoagulation/hemostasis, the coagulation/hemostasis portion of theelectrode 25 preferably comprises a greater surface area than the bluntor electrosurgical dissection portion of the electrode 25.

As shown in FIG. 36, preferably the cross-sectional dimension Z, of theknuckle portion 61 is greater than cross-section dimension F of thefinger portion 65. Here, as shown, the cross-sectional dimensions Z andF comprise diameters. However, in other embodiments where thecross-sectional dimension Z and/or F could not properly be considered tocomprise a diameter, the cross-sectional dimension Z and/or F couldcomprise a width or thickness.

Preferably, the cross-sectional dimension Z of the knuckle portion 61 isin the range between and including about 1.6 to 3.3 times greater thanthe cross-section dimension F of the finger portion 65, with typicaldimensions comprising the ratios of 2.5 mm to 1.5 mm (1.6 times) and 2.5mm to 0.75 mm (3.3 times). Even more preferably, the cross-sectionaldimension Z of the knuckle portion 61 is in the range between andincluding about 2 to 2.5 times greater than the cross-section dimensionF of the finger portion 65, with typical dimensions comprising theratios of 2.5 mm to 1.25 mm (2 times) and 2.5 mm to 1 mm (2.5 times).

From the above dimensions, the ratio of the surface area of the knuckleportion 61 to the surface area of the distal end (e.g. surface 42) ofthe finger portion 65 may be determined to an approximation using aformula for half the area of a sphere. For the above dimensions,preferably the surface area of the knuckle portion 61 is in the rangebetween and including about 2.8 times to 11 times greater than thesurface area the distal end of the finger portion 65. More preferably,the surface area of the knuckle portion 61 is in the range between andincluding about 4 times to 6.2 times greater than the surface area thedistal end of the finger portion 65.

Also as shown in FIGS. 39 and 40, neck portion 56 preferably comprises acylindrical portion 57 located proximal and adjacent to a spatulaportion 67. As shown, spatula portion 67 comprises a substantially flatanterior surface portion 69 of electrode 25. In certain embodiments,electrode 25 may comprise one, any combination of, or all of thefeatures of finger portion 65, knuckle portion 61 and spatula portion67.

Turning to use of the devices, similar to device 5 b, device 5 c isparticularly useful to a surgeon performing a liver resection. Once theouter capsule of the liver is scored with a dry bovie blade along theplanned line of resection the distal tip of tip portion 45 is paintedback and forth along the line, with radio frequency power and the flowof fluid 24 on, resulting in coagulation of the liver parenchyma. Oncethe tissue is coagulated under and around the electrode surface 42 and,as the device 5 c enters a crevice 97, surface 40, surface 42 ofelectrode 25 is used to blunt dissect the coagulated parenchyma. Bluntdissection of the coagulated parenchyma is performed by continuousabrading or splitting apart of the parenchyma with the substantially thesame back and forth motion as coagulation and with the device 5 c beingheld substantially in the same orientation as for coagulation of theliver parenchyma. However, with blunt dissection, the surgeon typicallyapplies more force to the tissue. In various embodiments, once the liverparenchyma is coagulated, blunt dissection may be performed with orwithout the radio frequency power (i.e. on or off) and/or with orwithout the presence of fluid 24.

In addition to liver resections, device 5 h are particularly useful to asurgeon performing a laparoscopic cholecystectomy (abbr. “lap chole”)for the case of, for instance, either acute cholecystitis or anintrahepatic gallbladder in that the device provides multi-functionaluses. More particularly, device 5 h is useful to the surgeon forcoagulation and dissection of an inflamed serosal layer of tissue 32between the liver and gallbladder, which may include tough, fibrous,highly vascular connecting tissue between the organs.

For coagulation, device 5 h may be positioned in at least threedifferent orientations. For the first orientation, as shown in FIG. 43,coagulation may be performed with posterior knuckle surface portion 62formed by knuckle portion 61. Similar to device 5 c, coagulation withdevice 5 h is performed with radio frequency power and the flow of fluid24 on. Preferably power is applied in the coagulation mode of thegenerator and at a power level in the range between and including about10 watts to 60 watts. More preferably, the power level is in the rangebetween and including about 20 watts to 50 watts. Even more preferably,the power level is in the range between and including about 30 watts to40 watts. With respect to motion of surface portion 62 duringcoagulation, coagulation may be performed with surface portion 62stationary, or with a painting motion by moving surface portion 62 backand forth substantially along the longitudinal axis 29 or laterally sideto side.

For the second orientation, as shown in FIG. 44, coagulation may beperformed with a combination of lateral knuckle surface portion 75formed by knuckle portion 61 and cylindrical surface portion 40, andmore specifically a lateral cylindrical surface portion of cylindricalsurface portion, of finger portion 65. For the third orientation, asshown in FIG. 45, coagulation may be performed also with anothercombination of knuckle portion 61 and finger portion 65. As shown inFIG. 45, coagulation may be performed with a posterior cylindricalsurface portion of cylindrical surface portion 40 and a posteriorsurface of knuckle portion 61. In the various orientations, coagulationmay be used to stop active bleeding (e.g. such as a spleen injurycomprising a splenic capsule tear) or pre-coagulation of tissue beforedissection for bloodless surgery.

Where the surgeon has pre-coagulated the tissue 32, the surgeon maydissect the tissue 32 with simultaneous mechanical traction (i.e. theprocess of drawing or pulling of the tissue 32 with a mechanical device)with anterior (i.e. front) surface portion 66 of finger portion 65 whichis configured, among other things, to engage and restrain tissue 32.More specifically, the surgeon may hook the tissue 32 for dissectionagainst the surface portion 66 of finger portion 65 and apply tractionto the tissue 32, then dissect the tissue 32.

Since the tissue 32 has been coagulated, dissection may be performedwith or without the radio frequency power (i.e. on or off) and/or withorwithout the presence of fluid 24. Where the tissue 32 is dissectedwithout fluid 24, but with the radio frequency power on and with thegenerator set to the coagulation mode, the process of dissecting may bereferred to as “hook and cook” in the art. While dissecting in thismanner is fast, it suffers from the problems of significant arcing, theproduction of smoke and char, and the possibility of inadvertentperforation of the gall bladder wall. Alternatively, dissecting withoutthe radio frequency power on may eliminate the problems of arcing, theproduction of smoke and char, and the possibility of inadvertentperforation, but may result in bleeding if the tissue 32 is notsufficiently coagulated. In order to overcome the aforementioned issues,dissection of the tissue 32 with traction may be performed similar tocoagulation (i.e. in the presence of both radio frequency power andfluid 24). However, this alternative typically requires more time than“hook and cook”.

With regards to the sequence of events for dissect the tissue 32 withtraction and using the “hook and cook” technique (i.e. without fluid24), the surgeon first engages the tissue 32 on the surface portion 66of finger portion 65. The surgeon then applies traction to the engagedtissue 32. Once complete, the surgeon checks for proper position thenapplies the radio frequency power. Upon application of the radiofrequency power, the tissue 32 yields, separates and breaks. The surgeonthen turns the radio frequency power off. This process may then berepeated numerous times as the surgeon incrementally dissects tissue 32along a length in step-wise fashion.

Certain embodiments of the invention may be particularly configured forbipolar devices. For example, an exemplary bipolar electrosurgicaldevice of the present invention which may be used in conjunction withthe system of the present invention is shown at reference character 5 iin FIGS. 46-48. With a bipolar device, the ground pad electrode locatedon the patient is eliminated and replaced with a second electrical poleas part of the device. An alternating current electrical circuit is thencreated between the first and second electrical poles of the device.Consequently, alternating current no longer flows through the patient'sbody to the ground pad electrode, but rather through a localized portionof tissue preferably between the poles of the bipolar device.

In certain embodiments, an exemplary bipolar surgical device of thepresent invention may comprise, among other things, multiple,substantially parallel, arms. As shown in FIG. 46, electrosurgicaldevice 5 i preferably includes two arms comprising rigid,self-supporting, hollow shafts 17 a, 17 b, a proximal handle comprisingmating handle portions 20 a, 20 b and arm tip portions as shown bycircles 45 a, 45 b. In this embodiment, shafts 17 a, 17 b preferablycomprise thick walled hypo-tubing. In this manner, the shafts 17 a, 17 bhave sufficient rigidity to maintain their form during use of the devicewithout kinking or significant bending.

Preferably the arms of device 5 i (comprising shafts 17 a, 17 b) areretained in position relative to each other by a mechanical couplingdevice comprising a collar 95 and inhibited from separating and/orrotating relative to each other. Collar 95 preferably comprises apolymer (e.g. acrylonitrile-butadiene-styrene or polycarbonate) and ispreferably located on the distal portion of the arms. More preferably,the collar 95 is located proximal the distal ends 53 a, 53 b of theshafts 17 a, 17 b. Preferably the collar 95 comprises two apertures 96a, 96 b, preferably comprising opposing C-shapes, configured to receivea portion of the shafts 17 a, 17 b which are preferably snap-fittherein. Once the collar 95 is connected to the shafts 17 a, 17 b,preferably by a snap-fit connection, the collar 95 may be configured toslide along the length of the shafts 17 a, 17 b as to adjust or vary thelocation of the collar 95 on the shafts 17 a, 17 b. Alternatively, thelocation of the collar 95 may be fixed relative to the shafts 17 a, 17 bby welding, for example.

Device 5 i comprises a first arm tip portion 45 a and a second arm tipportion 45 b. As shown, preferably both first arm tip portion 45 a andsecond arm tip portion 45 b are each individually configured identicalto tip portion 45 of device 5 a. As a result, device 5 i has twoseparate, spatially separated (by empty space) contact elementspreferably comprising electrodes 25 a, 25 b.

As shown in FIG. 47, when device 5 i is in use electrodes 25 a, 25 b arelaterally spaced adjacent tissue surface 22 of tissue 32. Electrodes 25a, 25 b are connected to a source of alternating electrical current andalternating current electrical field is created between electrodes 25 aand 25 b. In the presence of alternating current, the electrodesalternate polarity between positive and negative charges with currentflow from the positive to negative charge.

Similar to device 5 a, for device 5 i fluid 24 is communicated from afluid source 1 within the lumens 23 a, 23 b of the shafts 17 a, 17 bthrough the lumens 89 a, 89 b and cavities 81 a, 81 b of the sleeves 82a, 82 b where it is expelled from around and on the surface 42 a, 42 bof the electrodes 25 a, 25 b. Also similar to device 5 a, as shown inFIG. 46A electrodes 25 a, 25 b of device 5 i may comprise a porousstructure as disclosed herein.

As with use of device 5 a, with use of device 5 i fluid couplings 30 a,30 b preferably comprising discrete, localized webs and more preferablycomprising a triangular shaped web or bead portion providing a film offluid 24 is provided between the surface 22 of the tissue 32 and theelectrodes 25 a, 25 a. When the user of electrosurgical device 5 iplaces the electrodes 25 a, 25 b at a tissue treatment site and movesthe electrodes 25 a, 25 b across the surface 22 of the tissue 32, fluid24 is expelled around and on the surfaces 42 a, 42 b of the electrodes25 a, 25 b at the distal ends 83 a, 83 b of the sleeves 82 a, 82 b andonto the surface 22 of the tissue 32 via couplings 30 a, 30 b. At thesame time, RF electrical energy, shown by electrical field lines 130, isprovided to the tissue 32 at the tissue surface 22 and below the tissuesurface 22 into the tissue 32 through the fluid couplings 25 a, 25 b.

As with device 5 a, the fluid 24, in addition to providing an electricalcoupling between the electrosurgical device 5 i and the tissue 32,lubricates the surface 22 of the tissue 32 and facilitates the movementof electrodes 25 a, 25 b across the surface 22 of the tissue 32. Duringmovement of the electrodes 25 a, 25 b the electrodes 25 a, 25 btypically slide across the surface 22 of the tissue 32, but also mayrotate as the electrodes 25 a, 25 b move across the surface 22 of thetissue 32. Typically the user of the electrosurgical device 5 i slidesthe electrodes 25 a, 25 b across the surface 22 of the tissue 32 backand forth with a painting motion while using the fluid 24 as, amongother things, a lubricating coating. Preferably the thickness of thefluid 24 between the distal end surface of the electrodes 25 a, 25 b andthe surface 22 of the tissue 32 at the outer edge of the couplings 30 a,30 b is in the range between and including about 0.05 mm to 1.5 mm. Morepreferably, the fluid 24 between the distal end surface of theelectrodes 25 a, 25 b and the surface 22 of the tissue 32 at the outeredge of the coupling 30 a, 30 b is in the range between and includingabout 0.1 mm to 0.3 mm. Also preferably, in certain embodiments, thedistal end tip of the electrode 25 contacts the surface 22 of tissue 32without any fluid 24 in between.

As shown in FIG. 48, the fluid coupling for device 5 i may comprise aconductive fluid bridge 27 between electrodes 25 a, 25 b which rests onthe surface 22 of the tissue 32 and forms a shunt between the electrodes25 a, 25 b. Given this scenario, a certain amount of RF energy may bediverted from going into the tissue 32 and actually pass between theelectrodes 25 a, 25 b via the conductive fluid bridge 27. This loss ofRF energy may slow down the process of coagulating tissue and producingthe desired hemostasis or aerostasis of the tissue.

In order to counteract the loss of energy through bridge 27, once enoughenergy has entered the bridge 27 to boil the fluid 24 of bridge 27, theloss of RF energy correspondingly decreases with the loss of the bridge27. Preferably energy is provided into the fluid 24 of the bridge 27 bymeans of heat dissipating from tissue 32.

Thus, where a high % boiling of the conductive fluid 24 of the bridge 24is created, the loss of RF energy through the bridge 27 may either bereduced or eliminated because all the fluid 24 of bridge 27 boils off ora large fraction of boiling creates enough disruption in the continuityof the bridge 27 to disrupt the electrical circuit through the bridge27. Thus, one control strategy of the present invention is to reduce thepresence of a conductive fluid shunt by increasing the % boiling of theconductive fluid.

Another embodiment of a bipolar device is shown at 5 j in FIGS. 49 and50. Similar to device 5 i, electrosurgical device 5 j preferablyincludes two arms comprising rigid, self-supporting, shafts 17 a, 17 b,a proximal handle comprising mating handle portions 20 a, 20 b and firstand second arm tip portions as shown by circles 45 a, 45 b. However, asshown in FIG. 50, unlike device 5 i, for device 5 j the shafts 17 a, 17b may comprise solid rods (i.e. do not have lumens) which provide forelectrical connection to a power source but do not have lumens forproviding conductive fluid through the sleeves 82 a, 82 b. Ratherconductive fluid 24 is preferably provided by means of a lumen 122 of aseparate fluid line 120, preferably comprising either a metal (e.g.stainless steel hypo-tubing) or polymer (e.g. PVC tubing) material,extending distally and substantially parallel to the arms along sideshafts 17 a, 17 b. In order to minimize the risk of clogging of thelumen 122 at the distal end outlet opening 124 of the fluid line 120, asshown, preferably the distal end 126 of the fluid line 120 is locatedproximal and adjacent to the distal end of the device 5 j and morepreferably, proximal to spherical surface portions 42 a, 42 b ofelectrodes 25 a, 25 b, or other tissue treating surfaces of electrodesas the electrode configurations vary.

Also as shown for device 5 j, the outlet opening 124 for the fluid line120 is preferably spaced uniformly between electrodes 25 a, 25 b suchthat conductive fluid 24 expelled from the outlet opening 124 may form afluid coupling comprising the a bridge 27 between the tissue surface 22and the surface 42 a, 42 b of each of the electrodes 25 a, 25 b. If acollar 95 is used with device 5 j preferably the collar contains a thirdC-shaped aperture to accommodate fluid line 120 there through.

In certain embodiments, at least a portion of the length of the two arms(comprising the shafts 17 a, 17 b and sleeves 82 a, 82 b) or the twoarms and fluid line 120 of device 5 j may be located and housed withinthe cavity 132, typically a lumen, of an elongated hollow tubularenclosure 128 as shown in FIG. 49. The elongated tubular enclosure 128may or may not be connected to the handle portions 20 a, 20 b. Where thetubular enclosure is not connected to the handle portions 20 a, 20 b,similar to collar 95, the tubular enclosure 128 may be configured toslide along the length of the shafts 17 b, 17 c as to adjust or vary thelocation of the enclosure 128 on the shafts 17 a, 17 b or,alternatively, may be fixed relative to the shafts 17 a, 17 b bywelding, for example.

The elongated tubular enclosure 128 may comprise, for example awrapping, such as shrink wrap polymer film or shrink wrap polymertubing, which may be formed and located with the surface of cavity 132against insulators 90 a, 90 b upon the application of heat thereto. Inthis manner, the elongated members shafts 17 a, 17 b or the shafts 17 a,17 b and fluid line 120, are retained in position relative to each otherand inhibited from separating relative to each other.

Another embodiment of a bipolar device is shown at 5 k in FIGS. 51-53.As shown in FIGS. 51 and 53, electrosurgical device 5 k preferablyincludes a housing comprising mating handle portions 20 a, 20 b andmating elongated shaft portions 134 a, 134 b forming a hollow shaft. Asbest shown in FIG. 51, shaft portions 134 a, 134 b, preferably comprisetwo semi-circular elongated portions which are connected to handleportions 20 a, 20 b, respectively, preferably as part of a unitary (i.e.single piece) polymer molding.

As best shown in FIG. 53, electrodes 25 a, 25 b are preferably assembleddirectly with shaft portions 134 a, 134 b adjacent the distal end ofshaft portions 134 a, 134 b. As shown, preferably electrodes 25 a, 25 bare mechanically assembled adjacent the distal end of shaft portions 134a, 134 b via a spool configuration. More specifically, preferablyelectrodes 25 a, 25 b comprise locking portions comprising proximalcircular flange portions 136 a, 136 b and distal circular flangeportions 138 a, 138 b separated and connected by circular spindles 140a, 140 b there between which form the respective spool configurations.

The circular recesses 142 a, 142 b formed between the proximal circularflange portions 136 a, 136 b and distal circular flange portions 138 a,138 b provides a receptacle for receiving semi-circular interlocking tabportions 144 a, 144 b of distal end portions 146 a, 146 b of shaftportions 134 a, 134 b.

During assembly, the interlocking tab portions of one of the shaftportions are first located in a portion of the recesses 142 a, 142 b ofelectrodes 25 a, 25 b. In other words, for example, electrodes 25 a, 25b may be first assembled with semi-circular interlocking tab portions144 a of distal end portion 146 a of shaft portion 134 a which thenoccupy a first semi-circular portion of circular recesses 142 a, 142 b.Then, once the electrodes 25 a, 25 b have been properly seated withrespect to the first shaft portion, here 134 a, the interlocking tabportions of the second shaft portion, here 144 b of shaft 134 b, arelocated in the remaining semi-circular portion of circular recesses 142a, 142 b. After the electrodes 25 a, 25 b have been properly seated withrespect to both shaft portions 134 a, 134 b and all remaining componentsare properly located, the shaft portions 134 a, 134 b and handleportions 20 a, 20 b may be assembled to one another by use of, forexample an adhesive (e.g. cyanoacrylate) or welding.

As best shown in FIG. 53, electrodes 25 a, 25 b of device 5 k preferablycomprise spherical portions 43 a, 43 b and a corresponding sphericalsurface portions 42 a, 42 b located at the distal end of the devicewhich provided a smooth, blunt contour outer surface. More specifically,as shown, the spherical portions 43 a, 43 b and spherical surfaceportion 42 a, 42 b further provide a domed, hemisphere (i.e. less than afall sphere) and hemispherical surface portion comprising preferablyabout 180 degrees. Also as shown in FIG. 53, electrodes 25 a, 25 bpreferably also comprise cylindrical portions 39 a, 39 b and acorresponding cylindrical surface portions 40 a, 40 b located proximaland adjacent to the spherical portions 43 a, 43 b and spherical surfaceportions 42 a, 42 b, respectively.

Electrodes 25 a, 25 b of device 5 k are preferably coupled to thegenerator 6 via wire conductors 38 a, 38 b of insulated wires 21 a, 21b. At their distal ends, conductors 38 a, 38 b may be coupled toelectrodes 25 a, 25 b by means of first being inserted into the lumens148 a, 148 b of hollow metal tubes 150 a, 150 b, such as hypo-tubes,then crimping the tubes 150 a, 150 b. The tubes 150 a, 150 b are thenpreferably inserted and retained in proximal end receptacles 152 a, 152b of electrodes 25 a, 25 b by an interference fit. Alternatively, tubes150 a, 150 b may be eliminated and wire conductors 38 a, 38 b may becoupled to electrodes 25 a, 25 b by welding, soldering, mechanicalfasteners or other suitable methods.

For device 5 k conductive fluid 24 is preferably provided by means of alumen 122 of a separate fluid line 120, preferably comprising either ametal (e.g. stainless steel hypo-tubing) or polymer (e.g. PVC tubing)material, extending distally and substantially parallel within the lumenof the shaft comprising shaft portions 134 a, 134 b.

Similar to device 5 j, in order to minimize the risk of clogging of thelumen 122 at the distal end outlet opening 124 of the fluid line 120, asshown, preferably the distal end 126 of the fluid line 120 is locatedproximal to the distal end of the device 5 k and more preferably,proximal to spherical surface portions 42 a, 42 b and cylindricalsurface portions 40 a, 40 b of electrodes 25 a, 25 b, or other tissuetreating surfaces of electrodes as the electrode configurations vary.

Also similar to device 5 j, for device 5 k the outlet opening 124 forthe fluid line 120 is preferably spaced uniformly between electrodes 25a, 25 b such that conductive fluid 24 expelled from the outlet opening124 may form a fluid coupling comprising the a bridge 27 between thetissue surface 22 and the surface 42 a, 42 b of each of the electrodes25 a, 25 b.

The effect of the bipolar devices of the present invention on tissue maybe varied by changing the separation distance between the contactelements. Consequently, as shown in FIG. 54, in contrast to certainother embodiments which the separation distance is unadjustable, bipolardevice 51 provides an adjustment mechanism for changing the separationdistance (either increasing or decreasing) between the electrodes 25 a,25 b. As shown in FIG. 54, the changing of the separation distancebetween the electrodes 25 a, 25 b is provided by a scissors typeadjustment mechanism with two arms 117 a, 117 b hinged relative to oneanother in the middle on a pivot 110 preferably comprising a pin. Device51 may also comprise a latching mechanism 111 which incrementally fixesthe position of the electrodes 25 a, 25 b relative to one another duringtissue treatment by increasing or decreasing the separation distance.

Furthermore, as shown, the arms 117 a, 117 b themselves are preferablyhinged on pivots 110 a and 110 b, also preferably comprising pins, whichdivide the arms 117 a, 117 b into proximal arm portions 118 a, 118 b anddistal arm portions 112 a, 112 b. Distal arm portions 112 a, 112 b arepreferably connected by a linkage 113 which keeps distal arm portions112 a, 112 b and electrodes 25 a, 25 b substantially parallel to oneanother with use of the device 51. As shown, linkage 113 comprises a bar114 fixed to distal arm portion 112 b and having an elongated opening116 therein. Linkage also comprises a pin 115 fixed to distal armportion 112 a which moves along and within the opening 116 during use ofthe device 51 with the changing of the separation distance betweenelectrodes 25 a, 25 b. For device 51, tip portions 45 a, 45 b mayparticularly comprise the configuration disclosed with device 5 i.

Another embodiment of a bipolar device is shown at 5 m in FIGS. 55-58.As best shown in FIGS. 55 and 56 and similar to device 5 i,electrosurgical device 5 m preferably includes two stationary, immobilearms comprising rigid, self-supporting, hollow shafts 17 a, 17 b. Shafts17 a, 17 b for device 5 m preferably comprise thick walled hypo-tubingproviding sufficient rigidity to maintain their form during use of thedevice without kinking or significant bending. In certain embodiments,shafts 17 a, 17 b may be hand malleable.

As shown throughout FIGS. 55-58 and similar to device 5 i, preferablythe arms of device 5 m (comprising shafts 17 a, 17 b) are retained inposition relative to each other by a mechanical coupling devicecomprising a collar 95 and inhibited from separating relative to eachother. Also as shown throughout FIGS. 55-58, collar 95 is preferablylocated on a distal portion of the arms. More preferably, the collar 95is located adjacent the distal ends 53 a, 53 b of the shafts 17 a, 17 b.As best shown in FIGS. 57 and 58, preferably the collar 95 comprises twoapertures 96 a, 96 b, shown as comprising C-shapes, configured toreceive a distal end portion of the shafts arms. Once the collar 95 ismechanically connected to the shafts 17 a, 17 b, preferably by asnap-fit or slide-through connection, the location of the collar 95 maybe further fixed relative to the shafts 17 a, 17 b by, for example,adhesive bonding the collar 95 to shaft insulators 90 a, 90 b. Suchadhesive bonding may be accomplished, for example, either by use of aseparate adhesive or autogenic bonding of the collar 95 to theinsulators 90 a, 90 b by, for example, welding such as ultrasonicwelding.

Collar 95 comprises an electrically insulating (dielectric) material. Insome embodiments, the electrically insulating material for collar 95 maycomprise a polymer, either thermoplastic or thermoset, reinforced orunreinforced, filled or unfilled. Exemplary polymer materials include,but are not limited to, polyacetal (POM), polyamide (PA), polyamideimide(PAI), polyetheretherketone (PEEK), polyetherimide (PEI),polyethersulfone (PES), polyimide (PI), polyphenylenesulfide (PPS),polyphthalamide (PPA), polysulfone (PSO), polytetrafluoroethylene (PTFE)and syndiotactic polystyrene (SPS). More preferably, the electricallyinsulating polymer comprises either a liquid crystal polymer and, moreparticularly, an aromatic liquid crystal polyester which is reinforcedwith glass fiber, such as Vectra® A130 from Ticona, or Ultem® 10% glassfilled polyetherimide from the General Electric Company. Exemplaryreinforcement materials for polymers include, but are not limited to,glass fibers and boron fibers. Exemplary filler materials for polymersinclude mica, calcium carbonate and boron nitride. Reinforcementmaterials for the polymer material may be preferable for increasedstrength while filler materials may be preferable for increased heatresistance and/or thermal conductivity. Still other electricallyinsulating materials for collar 95 may a ceramic such as boron nitride.

As discussed above with reference to device 5 i and FIG. 48, the fluidcoupling to tissue for device 5 i may comprise a conductive fluid bridge27 between electrodes 25 a, 25 b which rests on the surface 22 of thetissue 32 and forms a shunt between the electrodes 25 a, 25 b. Asdiscussed above, a certain amount of RF energy may be diverted fromgoing into the tissue 32 and actually pass between the electrodes 25 a,25 b via the conductive fluid bridge 27. This loss of RF energy may slowdown the process of coagulating tissue and producing the desiredhemostasis or aerostasis of the tissue. Also as discussed above, theloss of RF energy through the bridge 27 may either be reduced oreliminated because all the fluid 24 of bridge 27 boils off or a largefraction of boiling creates enough disruption in the continuity of thebridge 27 to disrupt the electrical circuit through the bridge 27. Thus,as indicated above one control strategy of the present invention is toreduce the presence of a conductive fluid shunt by increasing the %boiling of the conductive fluid.

Rather than increasing the % boiling of the conductive fluid bridge 27to reduce the presence of a fluid shunt between the electrodes 25 a, 25b, in certain applications it may be advantageous to provide theelectrosurgical device with a dam between the electrodes 25 a, 25 bwhich reduces, and preferably prevents, the formation of the conductivefluid bridge 27 between the electrodes 25 a, 25 b.

As best shown in FIGS. 57 and 58, collar 95 of device 5 m preferablyfurther includes a substantially flat, blade-shaped electrical insulatorspacer portion 154 located laterally between the electrodes 25 a, 25 b.In addition to keeping the electrodes 25 a, 25 b separated at apredetermined minimum separation distance (as dictated by the thicknessof spacer portion 154), spacer portion 154 also provides a dam betweenelectrodes 25 a, 25 b which reduces, and preferably prevents, theformation of the conductive fluid bridge 27 between the electrodes 25 a,25 b.

Also as best shown in FIGS. 57 and 58, the distal end surface 156 ofspacer portion 154 preferably follows the contour of the adjacent distalend surfaces 158 a, 158 b of the electrodes 25 a, 25 b such that thedistal end surface 156 of spacer portion 154 is substantially flush, andpreferably flush, with the adjacent distal end surfaces 158 a, 158 b ofelectrodes 25 a, 25 b. In this manner, the spacer portion 156 and theelectrodes 25 a, 25 b are better configured to slide along the surfaceof tissue given there are no raised or recessed edges created betweenthe distal end surface 156 of spacer portion 154 and the adjacent distalend surfaces 158 a, 158 b of the electrodes 25 a, 25 b which couldimpair sliding movement.

Similar to device 5 c, electrodes 25 a, 25 b of device 5 m arepreferably assembled adjacent the distal ends 53 a, 53 b of shafts 17 a,17 b by connector portions, preferably comprising shank portions 46 a,46 b which connect the remainder of the electrodes 25 a, 25 b to shafts17 a, 17 b. Among other things, the connector portion of the electrodes25 a, 25 b are preferably configured to form a connection with a matingconnector portion of the shafts 17 a, 17 b. Also similar to device 5 c,preferably shank portions 46 a, 46 b of device 5 m are configured toextend into cavities 50 a, 50 b of shafts 17 a, 17 b which comprisecylindrical receptacles and provide the mating connector portions forshank portions 46 a, 46 b. Also similar to device 5 c, preferablysurfaces 48 a, 48 b of shank portions 46 a, 46 b of device 5 m areconfigured to mate against and form an interference fit with surfaces 52a, 52 b of cavities 50 a, 50 b to provide the connection.

Similar to device 5 c, shank portions 46 a, 46 b of device 5 m arepreferably cylindrical and located proximal and adjacent to neckportions 56 a, 56 b. As best shown in FIGS. 57 and 58, neck portions 56a, 56 b comprise cylindrical portions 57 a, 57 b preferably having across-sectional dimension, here diameter, greater than thecross-sectional dimension, here also diameter, of shank portions 46 a,46 b. In this manner, similar to device 5 c, in certain embodiments, theproximal end of neck portions 56 a, 56 b of device 5 m may be locatedadjacent and in contact with distal ends 53 a, 53 b of shafts 17 a, 17b.

As best shown in FIGS. 57 and 58, similar to recess 64 of device 5 c,electrodes 25 a, 25 b of device 5 m preferably comprises at least onerecess 63 a, 63 b which provides an elongated fluid flow channel andoutlet for the distribution of fluid 24.

Electrodes 25 a, 25 b of device 5 m preferably comprise an enlarged headportion. Each enlarged head portion preferably comprises a sidehemispherical portion 160 a, 160 b with a hemispherical surfacecomprising preferably about 180 degrees. As best shown in FIGS. 57 and58, preferably the hemisphere portions 160 a, 160 b are arranged facingaway from one another in outwardly facing opposing relation on oppositesides of the device. The hemispherical portions 160 a, 160 b arepreferably located laterally of transversely orientated cylindricalmedial transition portions 162 a, 162 b which preferably provide thesmooth transition between the hemispherical portions 160 a, 160 b andspacer portion 154 of collar 95. As shown electrodes 25 a, 26 b andspacer portion 154 may comprise abutting flat surfaces 164 a, 164 bwhich are arranged facing towards and opposing one another. Inalternative embodiments, medial transition portions 162 a, 162 b ofelectrodes 25 a, 25 b may be eliminated resulting in the head portion ofelectrodes 25 a, 25 b comprising just hemispherical portions 160 a, 160b with a hemispherical surfaces comprising preferably about 180 degrees.

In certain embodiments spacer portion 154 may comprise a thickness inthe range between and including about 0.5 mm to 10 mm, or in any 0.1 mmincrement or range therebetween, to provide a separation distancebetween the electrodes 25 a, 25 b of such. For example, spacer portion154 comprises a thickness in the range between and including about 1.5mm to 4 mm.

As an alternative to adjusting the separation distance between theelectrodes 25 a, 25 b by changing the thickness of the spacer portion154, portions of electrodes 25 a, 25 b may be coated with an thin (e.g.0.01 to 0.5 mm) electrically insulating coating comprising, for example,a polymer or ceramic material. As shown in FIGS. 59-62, a portion of theelectrodes 25 a, 25 b for device 5 n, here the neck portions 56 a, 56 b,medial transition portions 162 a, 162 b and approximately half of eachhemisphere portion 160 a, 160 b of the enlarged head portion are shownwith an electrically insulating coating 166 thereon. As a result, theactive tissue treating electrode surface is now limited to aboutquarter-sphere surfaces 168 a, 168 b and the separation distance betweenthe tissue treating electrode surfaces has been increased by thethickness of the medial transition portions 162 a, 162 b of electrodes25 a, 25 b.

Another embodiment of a bipolar device is shown at 5 o in FIGS. 63-64.Similar to device 5 n, the active tissue treating electrode surface ofelectrodes 25 a, 25 b may be limited to about quarter-sphere surfaces168 a, 168 b (about 90 degrees) with the other surfaces of the electrodeextending from the distal end of shaft insulators 90 a, 90 b havingelectrically insulating coating 166 thereon. However, different fromdevice 5 n, the enlarged head portion of the electrodes 25 a, 25 b ofdevice 5 o comprise two substantially circular spheres (i.e. exceptwhere they join to neck portions 56 a, 56 b). The spheres may have anysuitable diameter. However, the spheres preferably have a diameter inthe range between and including about 0.5 mm to about 7 mm. Morepreferably the spheres have a diameter in the range between andincluding about 1.0 mm to about 4 mm. Even more preferably, the sphereshave a diameter in the range between and including about 1.5 mm to about3 mm. Where coating 166 is not located thereon, the active electricalsurface of the spheres is about 260 degrees.

Also different from device 5 n, collar 95 of device 5 o does not includespacer portion 154. With device 5 o, electrodes 25 a, 25 b are separatedby an air gap therebetween. As a result, as shown in FIG. 64, whenelectrodes 25 a, 25 b of device 5 o are pressed against the surface 22of tissue 32 and the tissue 32 against electrodes 25 a, 25 b compressesand forms recesses 170 a, 170 b, device 5 o is configured to allowtissue 32 located adjacent the gap 172 between the electrodes 25 a, 25 bto form a tissue protuberance 174 there into with downward slopes intothe recess 170 a, 170 b. Since fluid 24 which may exist between theelectrodes 25 a, 25 b will tend to flow with gravity down the slopes ofthe tissue protuberance 174 and into the adjoining recesses 170 a, 170b, the possibility of formation of a conductive fluid bridge 27 betweenelectrodes 25 a, 25 b is reduced. Furthermore, even if a conductivefluid bridge 27 where to form between the electrodes 25 a, 25 b (e.g.where electrodes 25 a, 25 b of device 5 o are not pressed against tissue32 significantly enough to form recesses 170 a, 170, the coating 166 onthe inner facing surfaces of the electrodes 25 a, 25 b reduces thepossibility such a bridge would be electrified by electrodes 25 a, 25 bdirectly.

Another embodiment of a bipolar device is shown at 5 p in FIGS. 65-69.As best shown in FIG. 66, the electrodes 25 a, 25 b now comprise ahollow metal tubes. More specifically, the distal end portion of thetubes comprise about a 90 degree bend (within about ±5 degrees) formingtwo right angle elbows and which curves the distal end portions towardseach other as they extend distally. Furthermore, the distal ends of thetubes are arranged facing towards and opposing one another.Consequently, the electrodes 25 a, 25 b are substantially mirror imagesof each other.

As shown in FIG. 66, collar 95 has been removed to better show thatpreferably the electrodes 25 a, 25 b comprise circular, stainless steelhypo-tubing. Where the electrodes 25 a, 25 b comprise separate piecesfrom shafts 17 a, 17 b, electrodes 25 a, 25 b of device 5 p arepreferably connected to shafts 17 a, 17 b by interference fit of theinner diameter of the shafts 17 a, 17 b with the inner diameter of theelectrodes 25 a, 25 b. However, in order to minimize the number ofcomponents and assembly thereof, preferably a single piece of continuoustubing provides both the shaft and the electrode. In other words, asshown, preferably the electrodes 25 a, 26 b are provided by the samepiece of tubing used for shafts 17 a, 17 b.

As best shown in FIGS. 67-69, preferably device 5 p includes a collar 95which includes an electrical insulator spacer portion 154 locatedlaterally between the electrodes 25 a, 25 b. Furthermore, spacer portion154 preferably includes at least one recess 176 a, 176 b which providesan elongated fluid flow channel and a portion of the fluid passage forthe distribution of fluid 24 from openings 178 a, 178 b. As shown, boththe distal end openings 180 a, 180 b of the tubes and openings 178 a,178 b of recesses 176 a, 176 b are positioned at a locationsubstantially inaccessible to direct contact with tissue or otherwiseconfigured away from direct contact with tissue as to not becomeoccluded by tissue with use of device 5 p.

Preferably spacer portion 154 includes protrusions 182 a, 182 b, andmore specifically semi-circular protrusions configured to fit intodistal end openings 180 a, 180 b and at least partially occlude openings180 a, 180 b. In this manner electrodes 25 a, 25 b are retained frommovement relative to spacer 154, as well as the rest of collar 95.

In certain embodiments, in order that heat may be transferred away fromelectrodes 25 a, 25 b by spacer portion 154, preferably the material forcollar 95 has a thermal conductivity k_(tc) at 300° K. (Kelvin) equal orgreater than about 0.01 watt/cm° K. More preferably, the material forcollar 95 has a thermal conductivity k_(tc) at 300° K. (Kelvin) equal orgreater than about 0.16 watt/cm° K. Even more preferably, the materialfor collar 95 has a thermal conductivity k_(tc) at 300° K. (Kelvin)equal or greater than about 0.35 watt/cm° K.

The use of openings 178 a, 178 b of recesses 176 a, 176 b for thedistribution of fluid 24 may be preferred to at least one fluid exitopening 184 a, 184 b which may be provided on the distal end side ofelectrodes 25 a, 25 b proximal to the distal end (see FIG. 66),particularly in deep tissue crevices where tissue can occlude fluid flowfrom openings 184 a, 184 b. However, as shown in FIGS. 70-71 for device5 q, where fluid exit openings 184 a, 184 b are positioned at a locationsubstantially inaccessible to direct contact with tissue or otherwiseconfigured away from direct contact with tissue as to not becomeoccluded by tissue (such as slots shown on the inner side wall of theelectrodes 25 a, 25 b adjacent the inner radius of the elbow bend anddistal end of the electrode), the openings 184 a, 184 b may be equallyeffective as openings 178 a, 178 b.

More particularly, as shown, openings 184 a, 184 b in FIG. 70-71, forexample, are closer to the inner radius of elbow bend than the otherradius of the elbow bend, which aids in reducing occlusion by tissue.However, in other embodiments, the fluid exit openings 184 a, 186 a maybe closer to the outer radius of elbow bend than the inner radius of theelbow bend, as shown in FIG. 66. Still, in other embodiments, the fluidexit openings 184 a, 186 a may be equidistant the outer radius of elbowbend and the inner radius of the elbow bend, as shown in FIG. 73.

Another embodiment of a bipolar device is shown at 5 r in FIGS. 72-73.As shown the distal end of spacer portion 154 includes a recess 186configured to allow tissue 32 to form a tissue protuberance 174 thereinto to reduce the possibility of formation of a conductive fluid bridge27 between electrodes 25 a, 25 b as discussed above.

One or more of the devices of the present invention may includeassemblies which control power and/or fluid flow to the tissue treatingportion of the device. The ability to control the flow of fluid from thedevice may provide certain advantages over a device not so equipped.These advantages include reducing the amount of fluid at the tissuetreatment site and the likelihood of having to apply suction to thetreatment site to remove fluid.

For device 5 s in FIGS. 74-79, a single multi-positional,multi-functional switch and valve assembly 190 comprises a switch button192. Button 192 protrudes through an aperture 194 formed in handleportions 20 a, 20 b. Button 192 is preferably integrally connected via asingle piece polymer molding to a proximally extending switch arm 196which provides a portion of a fluid flow control mechanism, preferablyformed when interacting with handle portion 20 a to turn the flow offluid 24 to the tissue treating portion of the device on (full flow,i.e. unregulated flow at fall flow rate through the tubing) and off (noflow).

More specifically, the fluid flow control mechanism of switch/valveassembly 190 is provided with the changing the separation distancebetween the proximal end portion 198 of switch arm 196 and wall section200 of handle portion 20 a as switch arm 196 is moved proximally anddistally along track 206 formed and defined by apertures 208 of ribs 210of handle portion 20 a in response to button 192 being moved proximallyand distally in switch button aperture 194.

As shown in FIG. 76, fluid line 4 b is located between proximal endportion 198 of switch arm 196 and wall section 200 of handle portion 20a. As button 192 and switch arm 196 are moved proximally by hand force,thus decreasing separation distance between proximal end portion 198 ofswitch arm 196 and wall section 200 of handle portion 20 a, fluid line 4b is externally squeezed and compressed therebetween and its lumencorrespondingly occluded to decrease, and preferably completely stop,the fluid flow rate. As exhibited by the above fluid flow controlmechanism, preferably the mechanism does not make contact with fluid 24,thus reducing the likelihood of inadvertent contamination.

Continuing with FIG. 76, preferably the fluid flow control mechanism ofswitch/valve assembly 190 comprises a mechanism which holds the arm 196in a fixed, locked position while compressing and occluding fluid line 4b. As shown, preferably the locking mechanism comprises a locking tab202 of handle portion 20 a which holds arm 196 in its locked rearwardposition by engaging a distal end portion 204 of switch arm 196.

Locking tab 202 is disengaged from distal end portion 204 of switch arm196 by depressing button 192. Upon depressing button 192, the distal endportion 204 of switch arm also separates from tab 202 and tab 202disengages from distal end portion 204. As best shown in FIG. 77,simultaneously switch arm 196 is forced distally by the decompression ofresilient fluid line 4 b such that tab 202 enters detent 212. Preferablyswitch arm 196 is also forced distally by decompression of a linearspring 228 which biases proximal movement of arm 196 to the switch's offposition against fluid line 4 b with compression thereof, and, withdecompression thereof, helps return the switch 192 to its on positionupon arm 196 being disengaged from tab 202. As shown, spring 228 issupported on arm 196 by circular post 234 and is compressed between aflange 238 located at the base of post 234 and one of ribs 210. Upondistal end portion 204 of arm 196 disengaging from tab 202, button 192and switch arm 196 may travel distally until tab 202 engages theproximal end 214 of detent 212.

Once the flow of fluid 24 has resumed, switch button 192 of switch/valveassembly 190 may now be depressed to activate the flow of electriccurrent to electrodes 25 a, 25 b. As discussed above, electrodes 25 a,25 b are preferably coupled to the generator 6 via wire conductors 38 a,38 b of insulated wires 21 a, 21 b. Here, for example, the active andreturn electrodes comprise electrodes 25 a, 25 b.

As shown in FIGS. 78-79, electrode 25 a is directly coupled to generator6 without any additional inclusion of an on/off switch with anassociated control circuit therebetween. However, in addition to beingdirectly coupled to generator 6, the electrical coupling of electrode 25b to generator 6 now includes the presence of two separated electricalcontacts 216 and 218 which, in the open position, create an open controlcircuit between electrode 25 b and generator 6. The wiring of thiselectrical control circuit with the generator 6 is known in the art anddiscussed briefly below.

As best shown in FIGS. 77-79, contacts 216 and 218 are disposed on aplatform 222 partially underling switch button 192 and arm 196. As bestshown in FIG. 78, contact 216 comprises a domed contact which overliescontact 218. In the open, or undepressed, position, contact 216 remainsseparated from underlying contact 218 by virtue of the domedconfiguration of contact 216, thus resulting in an open control circuitbetween electrode 25 b and generator 6. However, when switch button 192of switch/valve assembly 190 is in its depressed position, post 220 inturn depresses dome contact 216 into contact with contact 218, thusclosing the control circuit between electrode 25 b and generator 6. Thepresence of the closed control circuit formed with wire 21 c is thensensed by generator 6 through a low voltage sensor which then providesthe set power to electrodes 25 a, 25 b.

When a depression force is removed from switch button 192, contact 216returns to its pre-depression domed position as a result of itsresiliency or elastic memory, thus returning switch button 192 to itsundepressed position and reopening the control circuit between electrode25 b and generator 6. The presence of the open control circuit is thensensed by the generator which then stops providing power to electrodes25 a, 25 b. Alternatively, where switch button 192 is not used and thephysician chooses to activate electrodes 25 a, 25 b with a foot pedalswitch, the set electrical power to the electrodes 25 a, 25 b only flowsdirectly through contact 218 to complete the electrical circuit.

It should be understood that switch/valve assembly 190 is configuredsuch that electrical current cannot be provided to electrodes 25 a, 25 bwhile the flow of fluid 24 is off. As shown in FIG. 77, when switchbutton 192 and switch arm 196 are in their proximal position, post 220does not overlie domed contact 216. Consequently, if switch button 192is depressed, post 220 merely makes contact with platform 222 and theelectrical circuit between electrodes 25 a, 25 b and generator 6 remainsopened.

It should also be understood that in the case of a single main fluidpassage which may branch into multiple secondary passages, preferablyswitch/valve assembly 190 acts on the main fluid passage to reducecomplexity. As shown in FIGS. 76-77, preferably switch/valve assembly190 is located proximal of splitter 240.

In other embodiments one or more of the devices of the present inventionmay include a separate power switch and fluid flow valve assemblesrather than part of a single multi-positional switch/valve assembly. Asshown in FIGS. 80-81, device 5 t comprises a switch assembly 224 forturning power on and off to the tissue treating portion of the deviceand a valve assembly 226 for turning fluid flow on (full flow) and off(no flow) to the tissue treating portion of the device.

As best shown in FIG. 81, switch button 230 of switch assembly 224 turnsfluid flow on and off in substantially the same manner as switch button192 of switch/valve assembly 190 (i.e. with distal and proximalmovement). However, unlike device 5 s, proximal end portion 198 ofswitch arm 196 of device 5 t includes a roller wheel 236 to aid withcompression and decompression of fluid line 4 b.

With regards to power, switch button 232 of valve assembly 226 turnspower on and off in substantially the same manner as switch button 192of switch/valve assembly 190 (i.e. in depressed and unpressedpositions). However, unlike switch/valve assembly 190, with valveassembly 226 power can be turned on and off independently of fluid flow.In other words, switch button 232 of valve assembly 226 can be in thepower “on” position while switch button 230 of switch assembly 224 is inthe fluid flow “off” position. Thus, the device 5 t can be configured tooperate as dry electrosurgical device without fluid 24 being providedsimultaneously from the tissue treating portion of the device.

In yet another embodiment, as shown in FIGS. 82-86, the second valveassembly for turning fluid flow on and off to the tissue treatingportion of the device may comprise a roller pinch clamp assembly. Asbest shown in FIGS. 83-86, device 5 u includes a roller pinch clampassembly 242 and, more specifically, an inclined ramp roller pinch clampassembly (as opposed to a parallel acting clamp).

As best shown in FIGS. 84-85, the clamp includes a housing provided byhandles 20 a, 20 b, a roller wheel 244 having a wheel center axis 246and a guide pin hub. As shown, the guide pin hub is provided by pair ofopposing, integrally formed, cylindrical trunnions 248 a, 248 b, but mayalso be provided by a separately formed pin. Trunnions 248 a, 248 b arecontained within and move along a track 250 preferably provided anddefined by opposing trunnion channels 252 a, 252 b formed between wheelupper guide surfaces 254 a, 254 b and wheel lower guide surfaces 256 a,256 b extending longitudinally and parallel inward from the side wallportions of the handles 20 a, 20 b. As shown, wheel upper guide surfaces254 a, 254 b are provided by a lip portion of the handles 20 a, 20 bwhich partially define aperture 258 through which roller wheel partiallyextends while wheel lower guide surfaces 256 a, 256 b are provided byribs 260 a, 260 b.

Handles 20 a, 20 b also preferably provide tubing guide surfaces 272 a,272 b which at least a portion of which provide a clamping surfaceagainst which plastic tubing 4 b is clamped by roller 244. As best shownin FIGS. 84-85, tubing guide surfaces 272 a, 272 b are provided by ribs270 a, 270 b. In use, fluid line 4 b is externally squeezed andcompressed between the outer perimeter surface 262 of roller wheel 244and at least a portion of tubing guide surfaces 272 a, 272 b. In thisembodiment, preferably surface 262 is serrated.

Trunnions 248 a, 248 b support the movement of roller wheel 244 in twoopposing directions, here proximally and distally, along track 250. Asbest shown in FIGS. 85-86, the separation distance between the outerperimeter surface 262 of roller wheel 244 and tubing guide surfaces 272a, 272 b changes throughout the proximal and distal travel of rollerwheel 244 along track 250. More specifically, the separation distancebetween the outer perimeter surface 262 of roller wheel 244 and tubingguide surfaces 272 a, 272 b is greater between the outer perimetersurface 262 of roller wheel 244 and distal end portions 274 a, 274 b oftubing guide surfaces 272 a, 272 b provided by distal end portions 264a, 264 b of ribs 270 a, 270 b than between the outer perimeter surface262 of roller wheel 244 and proximal end portions 276 a, 276 b of tubingguide surfaces 272 a, 272 b provided by proximal end portions 266 a, 266b of ribs 270 a, 270 b.

As shown in FIGS. 84-85, when axis 246 of roller wheel 244 is opposingdistal end portions 274 a, 274 b of tubing guide surfaces 272 a, 272 b,preferably the separation distance is configured such that the tubing 4b may be uncompressed and the lumen of tubing 4 b completely open forfull flow therethrough. Conversely, as shown in FIG. 86, when axis 246of roller wheel 244 is opposing proximal end portions 276 a, 276 b oftubing guide surfaces 272 a, 272 b preferably the separation distance isconfigured such that the tubing 4 b is compressed and the lumen oftubing 4 b is completely blocked so that the flow of fluid throughtubing 4 b is prevented.

Distal end portions 274 a, 274 b of tubing guide surfaces 272 a, 272 bare separated from proximal end portions 276 a, 276 b of tubing guidesurfaces 272 a, 272 b by transition surfaces 278 a, 278 b which areprovided by transition rib portion 268 a, 268 b of ribs 270 a, 270 b.Preferably compression of tubing initially begins between transitionsurfaces 278 a, 278 b and the outer perimeter surface 262 of rollerwheel 244 and increases as wheel 244 moves proximally along proximal endportions 276 a, 276 b of tubing guide surfaces 272 a, 272 b. With thisconfiguration, consideration may be given to eliminating at least thatportion of distal end portions 274 a, 274 b of tubing guide surfaces 272a, 272 b that do not contribute to compression of the tubing 4 b.However, given that of distal end portions 274 a, 274 b of tubing guidesurfaces 272 a, 272 b guide tubing 4 b to splitter 240, such may not bedesirable.

As shown in FIGS. 84-86, both transition surfaces 278 a, 278 b andproximal end portions 276 a, 276 b of tubing guide surfaces 272 a, 272 bprovide sloped inclining surfaces proximally along their respectivelengths which decreases the separation distance between the outerperimeter surface 262 of roller wheel 244 and the tubing guide surfaces272 a, 272 b as the wheel 244 moves proximally. As shown, preferably thetransition surfaces 278 a, 278 b and proximal end portions 276 a, 276 bof tubing guide surfaces 272 a, 272 b have different slopes such thatthe separation distance decreases at a faster rate along transitionsurfaces 278 a, 278 b as compared to proximal end portions 276 a, 276 bof tubing guide surfaces 272 a, 272 b. In this manner, compression oftubing 4 b is non-linear along the length of travel of wheel 244 with amajority of the compression occurring between roller wheel 244 andtransition surfaces 278 a, 278 b. More preferably, the lumen of tubing 4b is completely blocked when roller wheel 244 is compressing the tubing4 b against the proximal portion of transition surfaces 278 a, 278 b,and the added compression of the tubing 4 b along proximal end portions276 a, 276 b of tubing guide surfaces 272 a, 272 b provides anadditional safety to assure complete blocking of the lumen even wherethere are variations in the tubing, such as the size of the lumen.

It should be realized that, due to the slope of the transition ribportion 268 a, 268 b, as the roller wheel 244 moves proximally relativeto transition surfaces 278 a, 278 b the lumen of tubing 4 b is blockedincrementally. Thus, in addition to providing an on/off mechanism, theroller pinch clamp assembly 242 can also be used to regulate the fluidflow rate between two non-zero flow values. It should also be realizedthat the roller pinch clamp assembly 242 of the device may be used inseries conjunction with another roller pinch clamp assembly which istypically provided as part of an IV set (i.e. IV bag, IV bag spike, dripchamber, connecting tubing, roller clamp, slide clamp, luer connector).When used in this manner, the roller pinch clamp assembly of the IV setmay be used to achieve a primary (major) adjustment for fluid flow rate,while the roller pinch clamp assembly 242 of the device may be used toachieve a secondary (more precise minor) adjustment for the fluid flowrate.

In another embodiment, as shown in FIGS. 87-89 for device 5 v, theroller pinch clamp assembly 242 may include a cover 280 which at leastpartially closes aperture 258 and/or conceals roller wheel 244. Amongother things, cover 280 reduces the possibility of undesirable foreignfluid (e.g. blood and other bodily fluids) from entering into theconfines of handle 20 a, 20 b through aperture 258. Furthermore, cover280 reduces the exposure of the internal mechanics of the roller pinchclamp assembly 242. In this manner, cover 280 reduces the possibility offoreign objects (e.g. practitioner's rubber gloves) from entering intothe confines of handle 20 a, 20 b through aperture 258 and gettingsnagged, for example, between the trunnions 248 a, 248 b and track 250.

As shown in FIGS. 88-89, preferably cover 280 overlies and movesdistally and proximally with roller wheel 244, and is configured toprovide a switch button portion 282 when wheel 244 is covered withinsemi-circular receptacle 284 and inaccessible to direct manipulation.Preferably cover 280 is configured to substantially close aperture 258regardless of the position of the wheel 244, preferably by means of adistal shield portion 286 and a proximal shield portion 288. Preferably,distal shield portion 286 and a proximal shield portion 288 each have alength equal to or greater than the length of aperture 258 minus thelength of switch button portion 282.

Also as shown, preferably cover 280 comprises a distal guide portion 290and a proximal guide portion 292 located beneath distal shield portion286 and a proximal shield portion 288 on opposing sides of wheel 244. Asshown proximal guide portion 292 and distal shield portion 286 bothcomprise rectangular guide pins and preferably move along a track 250similarly to wheel 244. Wheel 244 partially extends into receptacle 284which has a slightly larger diameter than wheel 244.

With movement of switch button portion 282 proximally by a proximaldirected force apply by, for example, a finger, the inner surface 294 ofdistal guide portion 290 makes contact with surface 262 of wheel 244 andpushes wheel proximally. Conversely, with movement of switch buttonportion 282 distally by a distally directed force apply by, for example,a finger, the inner surface 296 of proximal guide portion 292 makescontact with outer surface 262 of wheel 244 and pushes wheel distally.In this embodiment, the surface 262 of wheel 244 is preferably smoothand wheel 244 preferably comprises a self-lubricating polymer materialsuch as polyacetal.

In another embodiment, as shown in FIGS. 90-91 for device 5 w, theswitch button portion 282 of cover 280 may include side portions 298which cover the opposing sides of wheel 244. However, unlike embodiment5 v, a portion of the cover 280 for device 5 w is not contained in ordirectly guided by track 250 as distal guide portion 290 and proximalguide portion 292 have been eliminated. While the cover 280 forembodiment 5 w still applies directional force to wheel 244 to movewheel 244, cover 280 now is joined to wheel 244 and conveyed along track250 by trunnions 248 a, 248 b of wheel 244. As shown, cover 280 includestwo opposing C-shaped apertures 300 which provided wheel hub receptaclesfor trunnions 248 a, 248 b. As shown, trunnions 248 a, 248 b are locatedin apertures 300.

Thus, with movement of switch button portion 282 proximally by aproximal directed force, the inner surface 302 of cover 280 definingapertures 300 makes contact with cylindrical side surface 304 oftrunnions 248 a, 248 b and pushes wheel proximally. Conversely, withmovement of switch button portion 282 distally by a distally directedforce, the inner surface 302 of cover 280 defining apertures 300 alsomakes contact with cylindrical side surface 304 of trunnions 248 a, 248b and pushes wheel distally.

In another embodiment, as shown in FIGS. 92-93 for device 5 x, theswitch button portion 282 of cover 280 has been eliminated. Thus, rollerwheel 244 is now exposed and may be acted on directly rather thanthrough switch button portion 282.

While the various embodiments of switch assembles described above havepredominately been described with reference to bipolar devices, itshould be understood that the various switch assemblies may be equallyadaptable to other fluid-assisted medical devices such as the monopolardevices of the present invention.

Bipolar devices 5 i-5 x are particularly useful as non-coaptive tissuesealers given they do not grasp tissue. Devices 5 i-5 x are particularlyuseful to surgeons to achieve hemostasis after dissecting through softtissue as part of hip or knee arthroplasty. The tissue treating portionscan be painted over the raw, oozing surface 22 of tissue 32 to seal thetissue 32 against bleeding, or focused on individual larger bleedingvessels to stop vessel bleeding.

Devices 5 i-5 x are also useful to stop bleeding from the surface of cutbone tissue as part of any orthopaedic procedure that requires bone tobe cut. Bipolar devices 5 i-5 x are particularly useful for theseapplications over a monopolar device 5 a as a much greater surface area22 of tissue 32 may be treated in an equivalent period of time and withbetter controlled depth of the treatment.

As is well known, bone, or osseous tissue, is a particular form of denseconnective tissue consisting of bone cells (osteocytes) embedded in amatrix of calcified intercellular substance. Bone matrix mainly containscollagen fibers and the minerals calcium carbonate, calcium phosphateand hydroxyapatite. Among the many types of bone within the human bodyare compact bone and cancellous bone. Compact bone is hard, dense bonethat forms the surface layers of bones and also the shafts of longbones. It is primarily made of haversian systems which are covered bythe periosteum. Compact bone contains discrete nutrient canals throughwhich blood vessels gain access to the haversian systems and the marrowcavity of long bones. For example, Volkmann's canals which are smallcanals found in compact bone through which blood vessels pass from theperiosteum and connect with the blood vessels of haversian canals or themarrow cavity. Bipolar devices as disclosed herein may be particularlyuseful to treat compact bone and to provide hemostasis and seal bleedingvessels (e.g. by shrinking to complete close) and other structuresassociated with Volkmann's canals and Haversian systems.

In contrast to compact bone, cancellous bone is spongy bone and formsthe bulk of the short, flat, and irregular bones and the ends of longbones. The network of osseous tissue that makes up the cancellous bonestructure comprises many small trabeculae, partially enclosing manyintercommunicating spaces filled with bone marrow. Consequently, due totheir trabecular structure, cancellous bones are more amorphous thancompact bones, and have many more channels with various blood cellprecursors mixed with capillaries, venules and arterioles. Bipolardevices as disclosed herein may be particularly useful to treatcancellous bone and to provide hemostasis and seal bleeding structuressuch as the above micro-vessels (i.e. capillaries, venules andarterioles) in addition to veins and arteries. Such devices may beparticularly useful for use during orthopaedic knee, hip, shoulder andspine procedures (e.g. arthroplasty).

During a knee replacement procedure, the condyle at the distal epiphysisof the femur and the tibial plateau at the proximal epiphysis of thetibia are often cut and made more planer with saw devices to ultimatelyprovide a more suitable support structure for the femoral condylarprosthesis and tibial prosthesis attached thereto, respectively. Thecutting of these long bones results in bleeding from the cancellous boneat each location. In order to seal and arrest the bleeding from thecancellous bone which has been exposed with the cutting of epiphysis ofeach long bone, the bipolar devices disclosed herein may be utilized.Thereafter, the respective prostheses may be attached.

Turning to a hip replacement procedure, the head and neck of the femurat the proximal epiphysis of the femur is removed, typically by cuttingwith a saw device, and the intertrochantic region of the femur is mademore planer to provide a more suitable support structure for the femoralstem prosthesis subsequently attached thereto. With respect to the hip,a ball reamer is often used to ream and enlarge the acetabulum of theinnominate (hip) bone to accommodate the insertion of an acetabular cupprosthesis therein, which will provide the socket into which the head ofthe femoral stem prosthesis fits. The cutting of the femur and reamingof the hip bone results in bleeding from the cancerous bone at eachlocation. In order to seal and arrest the bleeding from the cancellousbone which has been cut and exposed, the bipolar devices disclosedherein may be utilized. Thereafter, as with the knee replacement, therespective prostheses may be attached.

The bipolar devices disclosed herein may be utilized for treatment ofconnective tissues, such as for shrinking intervertebral discs duringspine surgery. Intervertebral discs are flexible pads offibrocartilaginous tissue tightly fixed between the vertebrae of thespine. The discs comprise a flat, circular capsule roughly an inch indiameter and about 0.25 inch thick, made of a tough, fibrous outermembrane called the annulus fibrosus, surrounding an elastic core calledthe nucleus pulposus.

Under stress, it is possible for the nucleus pulposus to swell andherniate, pushing through a weak spot in the annulus fibrosus membraneof the disc and into the spinal canel. Consequently, all or part of thenucleus pulposus material may protrude through the weak spot, causingpressure against surrounding nerves which results in pain andimmobility.

The bipolar devices disclosed herein may be utilized to shrinkprotruding and herniated intervertebral discs which, upon shrinkingtowards normal size, reduces the pressure on the surrounding nerves andrelieves the pain and immobility. The devices disclosed herein may beapplied via posterior spinal access under surgeon control for eitherfocal shrinking of the annulus fibrosus membrane.

Where a intervertebral disc cannot be repaired and must be removed aspart of a discectomy, the devices disclosed herein may be particularlyuseful to seal and arrest bleeding from the cancellous bone of opposingupper and lower vertebra surfaces (e.g. the cephalad surface of thevertebral body of a superior vertebra and the caudad surface of aninferior vertebra). Where the disc is removed from the front of thepatient, for example, as part of an anterior, thoracic spine procedure,the devices disclosed herein may also be particularly useful to seal andarrest bleeding from segmental vessels over the vertebral body.

The bipolar devices disclosed herein may be utilized to seal and arrestbleeding of epidural veins which bleed as a result of the removal oftissue around the dural membrane during, for example a laminectomy orother neurosurgical surgery. The epidural veins may start bleeding whenthe dura is retracted off of them as part of a decompression. Alsoduring a laminectomy, the devices disclosed herein, may be used to sealand arrest bleeding from the vertebral arch and, in particular thelamina of the vertebral arch.

One or more of the features of the previously described system can bebuilt into a custom RF generator. This embodiment can provide one ormore advantages. For example, this type of system can save space andreduce overall complexity for the user. This system can also enable themanufacturer to increase the power delivered into low impedance loads,thereby further reducing the time to achieve the desired tissue effects.This changes the curve of FIG. 5, by eliminating or reducing the slopeof the low impedance ramp 28 a of power versus impedance.

Alternatively, for situations where the high impedance ramp 28 b may beexceeded with use of the devices of the present invention, it may bedesirable to provide an impedance transformer 224 in a series circuitconfiguration between the electrode(s) of the device 5 and the poweroutput of generator 6. Consequently, the impedance transformer 224 maybe provided with the device 5, the generator 6 or any of the wireconnectors (e.g. wire 21) connecting device 5 and generator 6. Impedancetransformer 224 is configured to match the load impedance provided togenerator 6 such that it is within the working range of the generator 6and, more preferably in the working range between the low and highcut-offs.

To effectively treat thick tissues, it can be advantageous to have theability to pulse the RF power on and off. Under some circumstances, thetemperature deep in tissue can rise quickly past the 100° C. desiccationpoint even though the electrode/tissue interface is boiling at 100° C.This manifests itself as “popping,” as steam generated deep in thetissue boils too fast and erupts toward the surface. In one embodimentof the invention, a switch is provided on the control device or customgenerator to allow the user to select a “pulse” mode of the RF power.Preferably, the RF power system in this embodiment is further controlledby software.

In some embodiments, it can be desirable to control the temperature ofthe conductive fluid before it is released from the electrosurgicaldevice. In one embodiment, a heat exchanger is provided for the outgoingsaline flow to either heat or chill the saline. The heat exchanger maybe provided as part of the electrosurgical device or as part of anotherpart of the system, such as within the enclosure 14. Pre-heating thesaline to a predetermined level below boiling reduces the transientwarm-up time of the device as RF is initially turned on, therebyreducing the time to cause coagulation of tissue. Alternatively,pre-chilling the saline is useful when the surgeon desires to protectcertain tissues at the electrode/tissue interface and treat only deepertissue. One exemplary application of this embodiment is the treatment ofvaricose veins, where it is desirable to avoid thermal damage to thesurface of the skin. At the same time, treatment is provided to shrinkunderlying blood vessels using thermal coagulation. The temperature ofthe conductive fluid prior to release from the surgical device cantherefore be controlled, to provide the desired treatment effect.

In another embodiment, the flow rate controller is modified to providefor a saline flow rate that results in greater than 100% boiling at thetissue treatment site. For example, the selection switch 12 of the flowrate controller 11 (shown in FIG. 1) can include settings thatcorrespond to 110%, 120% and greater percentages of boiling. Thesehigher settings can be of value to a surgeon in such situations as whenencountering thick tissue, wherein the thickness of the tissue canincrease conduction away from the electrode jaws. Since the basiccontrol strategy neglects heat conduction, setting for 100% boiling canresult in 80% of 90% boiling, depending upon the amount of conduction.Given the teachings herein, the switch of the flow rate controller canaccommodate any desirable flow rate settings, to achieve the desiredsaline boiling at the tissue treatment site.

Some embodiments of the invention can provide one or more advantagesover current electrosurgical techniques and devices. For example, theinvention preferably achieves the desired tissue effect (for example,coagulation, cutting, and the like) in a fast manner. In a preferredembodiment, by actively controlling the flow rate of saline, both inquantity (Q vs. P) and location (for example, using gutters to directfluid distally to tissue, using holes to direct flow of fluid, or othersimilar methods) the electrosurgical device can create a hotnon-desiccating electrode/tissue interface and thus a fast thermallyinduced tissue coagulation effect.

The use of the disclosed devices can result in significantly lower bloodloss during surgical procedures such as liver resections. Typical bloodloss for a right hepatectomy can be in the range of 500-1,000 cubiccentimeters. Use of the devices disclosed herein to performpre-transection coagulation of the liver can result in blood loss in therange of 50-300 cubic centimeters. Such a reduction in blood loss canreduce or eliminate the need for blood transfusions, and thus the costand negative clinical consequences associated with blood transfusions,such as prolonged hospitalization and a greater likelihood of cancerrecurrence. Use of the device can also provide improved sealing of bileducts, and reduce the incidence of post-operative bile leakage, which isconsidered a major surgical complication.

The invention can, in some embodiments, deliver fast treatment of tissuewithout using a temperature sensor built into the device or a customspecial-purpose generator. In a preferred embodiment, there is nobuilt-in temperature sensor or other type of tissue sensor, nor is thereany custom generator. Preferably, the invention provides a means forcontrolling the flow rate to the device such that the device and flowrate controller can be used with a wide variety of general-purposegenerators. Any general-purpose generator is useable in connection withthe fluid delivery system and flow rate controller to provide thedesired power; the flow rate controller will accept the power andconstantly adjust the saline flow rate according to the controlstrategy. Preferably, the generator is not actively controlled by theinvention, so that standard generators are useable according to theinvention. Preferably, there is no active feedback from the device andthe control of the saline flow rate is “open loop.” Thus, in thisembodiment, the control of saline flow rate is not dependent onfeedback, but rather the measurement of the RF power going out to thedevice.

For purposes of the appended claims, the term “tissue” includes, but isnot limited to, organs (e.g. liver, lung, spleen, gallbladder), highlyvascular tissues (e.g. liver, spleen), soft and hard tissues (e.g.adipose, areolar, bone, bronchus-associated lymphoid, cancellous,chondroid, chordal, chromaffin, cicatricial, connective, elastic,embryonic, endothelial, epithelial, erectile, fatty, fibrous,gelatiginous, glandular, granulation, homologous, indifferent,interstitial, lymphadenoid, lymphoid, mesenchymal, mucosa-associatedlymphoid, mucous, muscular, myeloid, nerve, osseous, reticular, scar,sclerous, skeletal, splenic, subcutaneous) and tissue masses (e.g.tumors).

While preferred embodiments of the present invention have beendescribed, it should be understood that various changes, adaptations andmodifications can be made therein without departing from the spirit ofthe invention and the scope of the appended claims. The scope of theinvention should, therefore, be determined not with reference to theabove description, but instead should be determined with reference tothe appended claims along with their full scope of equivalents.Furthermore, it should be understood that the appended claims do notnecessarily comprise the broadest scope of the invention which theApplicant is entitled to claim, or the only manner(s) in which theinvention may be claimed, or that all recited features are necessary.

All publications and patent documents cited in this application areincorporated by reference in their entirety for all purposes.

1. A bipolar electrosurgical device comprising: a handle; at least onerigid shaft extending from the handle, the rigid shaft having a distalend; a first electrode tip spaced from a second electrode tip, the firstelectrode tip to serve as a first pole of a bipolar electrodeconfiguration and the second electrode tip to serve as a second pole ofthe bipolar electrode configuration, the first electrode tip and thesecond electrode tip adjacent the distal end of the shaft and the firstand the second electrode tips connected with first and second bipolarconnectors, respectively, connectable to a bipolar power output of agenerator to generate an electrical current flow between the electrodetips; at least one fluid delivery passage; each of the first electrodetip and the second electrode tip comprising an electrically conductivematerial having a porous structure; and the porous structure of thefirst electrode tip and the second electrode tip in fluid communicationwith the at least one fluid delivery passage.
 2. The device according toclaim 1 wherein: the first electrode tip and the second electrode tipare substantially parallel.
 3. The device according to claim 1 wherein:the first electrode tip and the second electrode tip are substantiallythe same shape.
 4. The device according to claim 1 wherein: the firstelectrode tip and the second electrode tip are substantially mirrorimages of each other.
 5. The device according to claim 1 wherein: thefirst electrode tip comprises a spherical distal end surface; and thesecond electrode tip comprises a spherical distal end surface.
 6. Thedevice according to claim 5 wherein: the first electrode tip sphericaldistal end surface comprises a spherical surface less than 180 degrees;and the second electrode tip spherical distal end surface comprises aspherical surface less than 180 degrees.
 7. The device according toclaim 5 wherein: the first electrode tip spherical distal end surfacecomprises a spherical surface of about 180 degrees; and the secondelectrode tip spherical distal end surface comprises a spherical surfaceof about 180 degrees.
 8. The device according to claim 5 wherein: thefirst electrode tip spherical distal end surface is provided by anexposed surface portion of a first electrically conductive ball; and thesecond electrode tip spherical distal end surface is provided by anexposed surface portion of a second electrically conductive ball.
 9. Thedevice according to claim 5 wherein: the first electrode tip comprises acylindrical surface; and the second electrode tip comprises acylindrical surface.
 10. The device according to claim 9 wherein: thefirst electrode tip cylindrical surface is located proximally adjacentto the first electrode tip spherical distal end surface; and the secondelectrode tip cylindrical surface is located proximally adjacent to thesecond electrode tip spherical distal end surface.
 11. The deviceaccording to claim 1 wherein: the first electrode tip comprises a domeddistal end surface; and the second electrode tip comprises a domeddistal end surface.
 12. The device according to claim 1 furthercomprising: a valve assembly to at least partially open and at leastpartially close the at least one fluid passage.
 13. The device accordingto claim 12 wherein: the at least one fluid passage is within a plastictubing; and the valve assembly comprises a roller clamp assembly, theroller clamp assembly having a wheel configured to roll along theplastic tubing to at least partially open and at least partially closethe fluid passage.
 14. The device according to claim 12 wherein: the atleast one fluid passage is within a plastic tubing; and the valveassembly is configured to move in a first direction and a seconddirection, the first direction to compress the plastic tubing to atleast partially close the fluid passage and a second direction todecompress the plastic tubing to at least partially open the fluidpassage.
 15. The device according to claim 12 wherein: the at least onefluid passage is within a plastic tubing; and the valve assemblycomprises a mechanism configured to at least one of compress and pinchthe plastic tubing to at least partially close the fluid passage. 16.The device according to claim 1 further comprising: a switch assembly tocontrol power, the switch assembly having on and off positions; a valveassembly to at least partially open and at least partially close the atleast one fluid passage, the valve having on and off positions; and amechanism which prevents the switch assembly from being in the onposition while the valve assembly is in the off position.
 17. The deviceaccording to claim 1 wherein: the electrically conductive material ofeach electrode tip comprises metal.
 18. The device according to claim 17wherein: the metal of each electrode tip comprises porous metal.
 19. Thedevice according to claim 17 wherein: the metal of each electrode tipcomprises a plurality of bonded metal particles.
 20. The deviceaccording to claim 17 wherein: the metal of each electrode tip comprisessintered metal.
 21. The device according to claim 1 wherein: the porousstructure of each electrode tip comprises pores having a pore size in arange of 2.5 micrometers to 500 micrometers.
 22. The device according toclaim 1 wherein: the porous structure of each electrode tip comprisespores having a pore size in a range of 10 micrometers to 120micrometers.
 23. The device according to claim 1 wherein: the porousstructure of each electrode tip comprises pores having a pore size in arange of 20 micrometers to 80 micrometers.
 24. The device according toclaim 1 wherein: the porous structure of each electrode tip comprises aplurality of tortuous pathways.
 25. The device according to claim 1wherein: the porous structure of each electrode tip comprises aplurality of interconnected tortuous pathways.
 26. The device accordingto claim 1 wherein: the porous structure of each electrode tip comprisesa porous surface.
 27. The device according to claim 1 wherein: theporous structure of each electrode tip is hydrophilic.
 28. The deviceaccording to claim 1 wherein: the at least one fluid delivery passagecomprises a first fluid delivery passage and a second fluid deliverypassage; the porous structure of the first electrode in fluidcommunication with the first fluid delivery passage; and a porousstructure of the second electrode in fluid communication with the secondfluid delivery passage.
 29. The device according to claim 1 wherein: theat least one fluid delivery passage is at least partially defined by afirst lumen and a second lumen; and the porous structure of the firstelectrode tip is in fluid communication with the first lumen and theporous structure of the second electrode tip is in fluid communicationwith the second lumen.
 30. A bipolar electrosurgical device comprising:a handle; at least one rigid shaft extending from the handle; at leastone fluid delivery passage; a plurality of electrodes adjacent a distalend of the shaft, the plurality of electrodes comprising a firstelectrode and a second electrode in a bipolar electrode configurationand connected with first and second bipolar connectors, respectively,connectable to a bipolar power output of a generator to generate anelectrical current flow between the electrodes; and each of the firstelectrode and the second electrode comprising an electrically conductivematerial having a porous structure in fluid communication with the atleast one fluid delivery passage.
 31. The device according to claim 30wherein: the electrically conductive material of each electrodecomprises metal.
 32. The device according to claim 31 wherein: the metalof each electrode comprises porous metal.
 33. The device according toclaim 31 wherein: the metal of each electrode comprises a plurality ofbonded metal particles.
 34. The device according to claim 31 wherein:the metal of each electrode comprises sintered metal.
 35. The deviceaccording to claim 30 wherein: the porous structure of each electrodecomprises pores having a pore size in a range of 2.5 micrometers to 500micrometers.
 36. The device according to claim 30 wherein: the porousstructure of each electrode comprises pores having a pore size in arange of 10 micrometers to 120 micrometers.
 37. The device according toclaim 30 wherein: the porous structure of each electrode comprises poreshaving a pore size in a range of 20 micrometers to 80 micrometers. 38.The device according to claim 30 wherein: the porous structure of eachelectrode comprises a plurality of tortuous pathways.
 39. The deviceaccording to claim 30 wherein: the porous structure of each electrodecomprises a plurality of interconnected tortuous pathways.
 40. Thedevice according to claim 30 wherein: the porous structure of eachelectrode comprises a porous surface.
 41. The device according to claim30 wherein: the porous structure of each electrode is hydrophilic. 42.The device according to claim 30 wherein: the at least one fluiddelivery passage comprises a first fluid delivery passage and a secondfluid delivery passage; the porous structure of the first electrode influid communication with the first fluid delivery passage; and a porousstructure of the second electrode in fluid communication with the secondfluid delivery passage.
 43. The device according to claim 30 wherein:the first electrode and the second electrodes are separated at adistance in a range of about 0.5 mm to 10 mm.
 44. The device accordingto claim 30 wherein: the first electrode and the second electrodes areseparated at a distance in a range of about 1.5 mm to 4 mm.
 45. Thedevice according to claim 30 wherein: the first electrode has a firstelectrode surface and the second electrode has a second electrodesurface; and the first electrode surface and the second electrodesurface are located at distal end of the device.
 46. The deviceaccording to claim 30 wherein: the first electrode has a first electrodesurface and the second electrode has a second electrode surface; and thefirst electrode surface and the second electrode surface are flush. 47.The device according to claim 30 wherein: the first electrode has afirst electrode surface and the second electrode has a second electrodesurface; and the first electrode surface and the second electrodesurface are substantially flush.
 48. The device according to claim 30wherein: an electrically insulative material is located between the twoelectrodes.
 49. The device according to claim 48 wherein: theelectrically insulative material has a thickness of 0.01 mm to 0.5 mm.50. The device according to claim 48 wherein: the electricallyinsulative material has a thickness of about 0.5 mm to 10 mm.
 51. Thedevice according to claim 30 wherein the first electrode and the secondelectrode are separated by a spacer.
 52. The device according to claim30 further comprising: a valve assembly to at least partially open andat least partially close the at least one fluid passage.
 53. The deviceaccording to claim 30 wherein: the at least one fluid delivery passageis at least partially defined by a first lumen and a second lumen; andthe porous structure of the first electrode tip is in fluidcommunication with the first lumen and the porous structure of thesecond electrode tip is in fluid communication with the second lumen.54. An electrosurgical system comprising: an electrosurgical generatorhaving a bipolar power output; and a bipolar electrosurgical deviceconfigured to be connected to the electrosurgical generator, the bipolarelectrosurgical device comprising: a handle; at least one rigid shaftextending from the handle; at least one fluid delivery passage; aplurality of electrodes adjacent a distal end of the shaft, theplurality of electrodes comprising a first electrode and a secondelectrode in a bipolar electrode configuration; and each of the firstelectrode and the second electrode comprising an electrically conductivematerial having a porous structure in fluid communication with the atleast one fluid delivery passage.
 55. The device according to claim 54wherein: the electrically conductive material of each electrodecomprises metal.
 56. The device according to claim 55 wherein: the metalof each electrode comprises porous metal.
 57. The device according toclaim 55 wherein: the metal of each electrode comprises a plurality ofbonded metal particles.
 58. The device according to claim 55 wherein:the metal of each electrode comprises sintered metal.
 59. The deviceaccording to claim 54 wherein: the porous structure of each electrodecomprises pores having a pore size in a range of 2.5 micrometers to 500micrometers.
 60. The device according to claim 54 wherein: the porousstructure of each electrode comprises pores having a pore size in arange of 10 micrometers to 120 micrometers.
 61. The device according toclaim 54 wherein: the porous structure of each electrode comprises poreshaving a pore size in a range of 20 micrometers to 80 micrometers. 62.The device according to claim 54 wherein: the porous structure of eachelectrode comprises a plurality of tortuous pathways.
 63. The deviceaccording to claim 54 wherein: the porous structure of each electrodecomprises a plurality of interconnected tortuous pathways.
 64. Thedevice according to claim 54 wherein: the porous structure of eachelectrode comprises a porous surface.
 65. The device according to claim54 wherein: the porous structure of each electrode is hydrophilic. 66.The device according to claim 54 wherein: the at least one fluiddelivery passage comprises a first fluid delivery passage and a secondfluid delivery passage; the porous structure of the first electrode influid communication with the first fluid delivery passage; and a porousstructure of the second electrode in fluid communication with the secondfluid delivery passage.
 67. The device according to claim 54 wherein:the first electrode and the second electrodes are separated at adistance in a range of about 0.5 mm to 10 mm.
 68. The device accordingto claim 54 wherein: the first electrode and the second electrodes areseparated at a distance in a range of about 1.5 mm to 4 mm.
 69. Thedevice according to claim 54 wherein: the first electrode has a firstelectrode surface and the second electrode has a second electrodesurface; and the first electrode surface and the second electrodesurface are located at distal end of the device.
 70. The deviceaccording to claim 54 wherein: the first electrode has a first electrodesurface and the second electrode has a second electrode surface; and thefirst electrode surface and the second electrode surface are flush. 71.The device according to claim 54 wherein: the first electrode has afirst electrode surface and the second electrode has a second electrodesurface; and the first electrode surface and the second electrodesurface are substantially flush.
 72. The device according to claim 54wherein: an electrically insulative material is located between the twoelectrodes.
 73. The device according to claim 72 wherein: theelectrically insulative material has a thickness of 0.01 mm to 0.5 mm.74. The device according to claim 72 wherein: the electricallyinsulative material has a thickness of about 0.5 mm to 10 mm.
 75. Thedevice according to claim 54 wherein: the first electrode and the secondelectrode are separated by a spacer.
 76. The device according to claim54 further comprising: a valve assembly to at least partially open andat least partially close the at least one fluid passage.
 77. The deviceaccording to claim 54 wherein: the at least one fluid delivery passageis at least partially defined by a first lumen and a second lumen; andthe porous structure of the first electrode tip is in fluidcommunication with the first lumen and the porous structure of thesecond electrode tip is in fluid communication with the second lumen.